Bottom line up front
Short answer: there is no national per-carat rate, but a loose one carat round at G colour and VS1 clarity works out at roughly R72,000 to R92,000 including VAT, with about R82,000 in the middle.
- Rebuild it yourself. The Rapaport round list of 20 March 2026 puts G/VS1 in the 1.00 to 1.49 carat band at $5,400 per carat. Nobody pays list, so take 10 to 30 percent off, convert at 16.50 rand to the dollar (the live rate on 4 August 2026) and add 15 percent VAT. At exactly one carat the total price and the price per carat are the same number, so that band is also a per-carat band.
- Every other weight and grade is priced further down this page. A full grid from 0.30 to 3.00 carat across seven common specifications, on that identical arithmetic. At 0.50 carat in G/VS1 it is roughly R12,500 to R16,000; at 2.00 carat, roughly R398,000 to R512,000.
- It is not linear. A two carat diamond does not cost twice a one carat of the same quality, it costs about five and a half times as much, and a one carat costs nearly six times a half carat. The per-carat rate itself climbs with weight. Multiply, and you will be wrong every time, in the same direction.
- Ask a manufacturer, cutting house or dealer for the number, and buy there. A retail counter buys its stones at exactly that level and then roughly doubles the price, about three times at a branded showroom, while the steps between one trade level and the next run at 3 to 5 percent. That single hop is where nearly all of the distance in a per-carat comparison comes from.
- They do the rest too. Setting, bespoke commissions, resizing, re-tipping, insurance valuations, repairs and buy-back, usually on their own bench, which is where a counter without a workshop sends the job anyway.
A counter is worth its premium when you need a finished ring by Saturday, when trying completed rings on decides it for you, or when the brand matters. The higher per-carat number is what those three things cost.
The band above is an estimate built on a published list plus one stated assumption, which is its whole value: you can redo it with today’s list and today’s rand. It holds at that weight, at that specification, and nowhere else.
That caveat is the subject of this page. A price per carat is not a national rate you look up and multiply, the way you would look up a gold price. It is the output of a grid, and the grid moves in two directions at once: the rate changes when you change the specification, and it changes again when you change the weight. Most buyers know the first half. Almost nobody is told the second, and the second is where the money is.
The non-linearity is worth one more sentence, because it is the half almost nobody is told. The per-carat rate itself climbs as stones get bigger, so a two carat of the same quality costs considerably more than twice a one carat, and the error from multiplying always runs the same way.
I work in the diamond trade, so weigh what follows accordingly.
What “price per carat” actually means
A carat is a unit of weight, not size. One carat is 200 milligrams. So a price per carat is a rate, and the arithmetic is simple:
Total price = price per carat, multiplied by carat weight.
This is how the trade genuinely quotes. The Rapaport price list, the reference nearly every polished stone in the world is priced against, gives each cell as a price per carat, and you multiply by the stone’s weight.
The trap is one silent assumption: that the rate is a property of diamonds in general and can be carried from one stone to the next. It is a property of one cell in a grid, and there are hundreds of cells.
The part nobody tells you: the rate rises with size
This is not opinion. It is visible in the structure of the price list. The Rapaport list is not one sheet. It is cut into separate sheets by carat weight band, with breaks at roughly 0.90 to 0.99, 1.00 to 1.49, 1.50 to 1.99, 2.00 to 2.99 and upward. Those bands exist for one reason: larger stones command higher prices per carat. If the rate were constant across weight, one sheet would do. The cause underneath is geological rather than commercial. Large gem-quality rough is far rarer than small, and rarity compounds with size.
Now put the two facts together. Going from one carat to two doubles the weight, and it also moves you into a higher per-carat band. Both factors rise, and they multiply. That is why the two carat is not double.
Here is the whole thing, priced. Every cell below is a loose round brilliant, stone only, including VAT, and every one is built the same way: the published round list for that exact weight bracket and grade, taken at 10 to 30 percent off list, converted at R16.50 to the dollar, plus 15 percent VAT. The width of each band is the discount, nothing else.
| Carat | D/VS1 | F/VS1 | G/VS1 | G/VS2 | H/VS1 | H/VS2 | I/SI1 |
|---|---|---|---|---|---|---|---|
| 0.30 | R7,000 to R8,500 | R5,500 to R7,000 | R5,000 to R6,500 | R5,000 to R6,000 | R5,000 to R6,000 | R4,500 to R5,500 | R4,000 to R5,000 |
| 0.50 | R16,500 to R21,500 | R14,000 to R18,000 | R12,500 to R16,000 | R12,000 to R15,500 | R11,500 to R14,500 | R10,500 to R13,500 | R8,500 to R11,000 |
| 0.70 | R32,500 to R42,000 | R28,000 to R36,000 | R25,000 to R32,500 | R22,500 to R28,500 | R21,500 to R27,500 | R19,500 to R25,000 | R15,000 to R19,000 |
| 0.90 | R63,500 to R81,500 | R52,500 to R67,500 | R48,000 to R61,500 | R42,000 to R54,000 | R40,500 to R52,500 | R37,000 to R47,500 | R28,500 to R37,000 |
| 1.00 | R101,000 to R130,000 | R83,500 to R108,000 | R71,500 to R92,000 | R62,500 to R80,500 | R60,000 to R77,000 | R56,000 to R71,500 | R41,000 to R53,000 |
| 1.50 | R253,000 to R325,000 | R215,000 to R277,000 | R187,000 to R241,000 | R169,000 to R218,000 | R153,000 to R197,000 | R139,000 to R179,000 | R106,000 to R136,000 |
| 2.00 | R545,000 to R700,000 | R465,000 to R598,000 | R398,000 to R512,000 | R359,000 to R461,000 | R332,000 to R427,000 | R305,000 to R393,000 | R228,000 to R294,000 |
| 3.00 | R1,395,000 to R1,793,000 | R1,176,000 to R1,511,000 | R976,000 to R1,255,000 | R837,000 to R1,076,000 | R817,000 to R1,050,000 | R737,000 to R948,000 | R558,000 to R717,000 |
Now read the G/VS1 column downward, because it settles the multiplication question this whole section is about.
- Half a carat to a full carat, double the weight, takes you from about R12,500 to R16,000 up to about R71,500 to R92,000. That is roughly five and three quarter times the money for twice the weight.
- One carat to two carat goes from about R71,500 to R92,000 up to about R398,000 to R512,000. Roughly five and a half times, again for twice the weight.
- One carat to three carat, three times the weight, is about thirteen and a half times the money.
- Read as a rate rather than a total, the per-carat price of a G/VS1 round climbs about twentyfold between 0.30 carat and 3.00 carat. That is the non-linearity, in one number.
So the multiplier is not two, and it is not one number either. It changes with the cell, the shape and the market on the day, which is exactly why the table is a grid rather than a formula. Take the two rows you are actually choosing between, read them across at your grade, and the multiplication has been done for you. Then ask a seller to quote both weights and see whether their step matches the list’s.
Downward it works the same way, which is the useful half for most budgets: a half carat of identical quality costs far less than half a one carat, and a 0.70 in G/VS1 at roughly R25,000 to R32,500 is about a third of the one carat while showing about 80 percent of its face-up area. That is why buyers short of a one carat budget are so often surprised by how much stone they get at 0.70, and why the 2 carat and 3 carat pages read so differently from the one carat page.
Three limits on that grid, and they are real rather than decorative. It is round brilliants only, because fancy shapes price off separate sheets. It is the loose stone only, with no setting, no making charge and no certification fee inside any figure. And it moves whenever the list moves or the rand moves, so the inputs are printed beside it deliberately: substitute today’s rate and redo the sum rather than quoting mine back at anyone.
The magic sizes, and the cheapest real saving in the market
Because the rate steps rather than glides, there are specific weights where the price jumps for no visible reason. The trade calls them magic sizes: 0.50, 0.70, 0.90, 1.00, 1.50 and 2.00 carat.
Two forces put them there. Demand concentrates on round numbers, because those are the numbers people ask for. And the price list bands break at the same points, so a stone crossing a threshold is repriced from a higher sheet. A cutter will fight to land a stone just above a line, because dropping below one costs real money on otherwise identical goods.
| Weight | Typical diameter, round brilliant | Face-up area vs a 1.00 ct | What happens at this point |
|---|---|---|---|
| 0.50 ct | 5.2 mm | about 64 percent | A demand threshold. Stones just under it are priced from a lower band. |
| 0.70 ct | 5.8 mm | about 80 percent | Popular value point. Frequently the most stone per rand in the market. |
| 0.90 ct | 6.2 mm | about 91 percent | Top of the band below one carat. The classic place to buy just under. |
| 1.00 ct | 6.5 mm | 100 percent | The largest single step in the market. Demand is heaviest here. |
| 1.50 ct | 7.4 mm | about 130 percent | Another band break, and the money involved is larger. |
| 2.00 ct | 8.2 mm | about 159 percent | Band break with the biggest rand consequence of the six. |
Diameters are the standard published reference figures for a well-proportioned round brilliant, the same ones used in the diamond size guide; the area column is calculated from them. Spread varies with cut, and the millimetre line on the grading report beats any chart.
The opportunity is in the third column. Doubling the weight from 1.00 to 2.00 carat buys about 59 percent more visible surface, while costing well over double. You are paying for weight that lives underneath the stone, where nobody looks.
The 0.98 against the 1.01
Take two stones of the same colour, clarity and cut make. One weighs 0.98 carat, the other 1.01. The 1.01 is priced from the one carat band, the 0.98 from the band below it. Between them lies three hundredths of a carat, which is six milligrams.
Calculated from the standard reference diameters at constant proportions, the 0.98 measures roughly 0.07 mm less across the top and shows about 98 percent of the face-up area of the 1.01. Seven hundredths of a millimetre. On a hand, in a photograph, across a dinner table, nobody can see that. On an invoice you can see it plainly.
The same trade applies at 1.90 against 2.00, where the rand difference is larger again. Buying just under a magic size is one of very few savings in this market that costs you nothing you can observe.
Two honest caveats. The certificate will read 0.98, not 1.00, and for some buyers the number on the paper is part of what they are buying. And a stone just under a threshold is marginally less liquid if you sell, because the next buyer wants the round number for the reason you were tempted by it.
The Rapaport list, explained properly
Most of what South Africans read about “Rap prices” is wrong, or is a sales tool. Here is the structure.
The Rapaport Price List is the diamond trade’s shared reference for polished stones. It is published weekly, and it is a grid: colour grades from D to M on one axis, clarity grades from IF to I3 on the other, with separate sheets by shape and by carat weight band. Every cell holds a price per carat, in hundreds of US dollars. To value a stone you find its cell, read the rate, and multiply by the weight.
Three consequences follow, and each breaks a comparison people make daily.
First, at any single weight there is not one price but dozens. A one carat has a cell at D/IF, a cell at M/I3, and everything between. Quoting “the per carat price of a one carat diamond” without naming the cell is like quoting the price of a car without naming the car.
Second, nobody in the trade pays list. Stones change hands at a discount, quoted as “Rap minus” a percentage. How deep it runs depends on the make, the shape, the weight band, the freshness of the stock and the market that week. I have not measured a South African figure for it, so there is no single verified percentage anywhere on this page. What the estimate at the top does instead is bracket the unknown: 10 percent off list at one end, 30 percent at the other, and 20 percent as a plausible middle for a dealer selling direct to a private buyer. That is an assumption, labelled as one, and you can substitute your own and rerun the arithmetic in a minute. A single percentage published as fact is the kind of number that gets repeated for years after it stops being true. Converting a Rap-minus quote into a real price is covered in the Rapaport price list explainer.
Third, it is a dollar reference, and you pay in rand. A Rap-minus number carries no exchange rate, no VAT, no import handling and no local margin, and the largest thing stacked on it afterwards is none of those. It is the retail step, covered below.
A deep discount off list on a soft stone can easily cost more, in real terms, than a tight discount on a good one. The percentage is not the point. The cell is.
Why comparing two per-carat prices is the most misleading thing a buyer can do
A per-carat number means something only when it is attached to a specific cell, at a specific weight band, on a specific basis. Strip any of that away and it keeps looking like a price while it stops behaving like one. Five things go wrong.
The specification is not matched. Colour and clarity are two axes of the grid and the two most likely to be quoted. Cut make is the one that usually is not, and at identical colour and clarity it moves the price materially. GIA grades cut on standard round brilliants only, so on a fancy shape there is no cut grade at all, and your protection is your own eye and someone willing to show you the stone.
The weight bands are different. A rate on a 0.90 against one on a 1.20 compares two different sheets. The bigger stone shows the higher rate almost regardless of whether it is the better buy.
The carat is not one stone. A “1 carat” that is a cluster or halo is a total carat weight spread across many small stones. Divide its price by one carat and the figure is arithmetically correct and completely meaningless, because ten stones of a tenth of a carat are worth a fraction of one crystal weighing a full carat. This is the most common per-carat trap in the South African market.
The basis is different. One quote is pre-VAT and loose, the other VAT-inclusive with a setting inside it. Neither is dishonest alone. Set against each other they produce a gap that has nothing to do with any diamond.
The two sellers are not stocking the same goods. This one has evidence behind it rather than logic. In June 2026 I recorded the specification of 230 individually listed GIA-certified natural diamonds at six South African sellers. Scored against a fixed definition of premium specification, D to G colour with VS2 clarity or better, 52 percent of the stock reachable through trade access met that bar, against 9 percent of the stock in South African retail cases. Roughly a fivefold difference in how much of the inventory a careful buyer would want.
Think about what that does to a per-carat average. If one pool is five times richer in high-specification material, averaging across the two rewards whoever stocks the weakest goods, because weak goods are cheap per carat. The table looks like it ranks value. It ranks inventory quality, upside down.
Where a genuine per-carat gap comes from
Match the specification perfectly and a gap can still remain. Now it means something, because the diamond is held constant and one variable is left: position in the supply chain.
Margins between one level of the trade and the next are thin, commonly 3 to 5 percent a hop. The large step happens once, at the end, when the stone leaves the trade for a retail counter. Retail convention is keystone, roughly double the cost, and a branded showroom runs to roughly three times. So the same certified stone can carry two very different per-carat numbers honestly. Knowing which part of your number bought the diamond and which part bought the shop is the whole exercise. Layer by layer in wholesale diamond pricing.
The method: how to compare per-carat quotes properly
Hold these nine things still, and whatever difference survives is real.
| Hold this constant | Why it moves the per-carat number | Where you check it |
|---|---|---|
| Exact carat weight | The rate itself steps between weight bands | The weight line on the grading report, not the advert |
| One stone, not total carat weight | A cluster’s per-carat figure is arithmetic across chips | Ask in writing. Watch for “total carat weight”, “twt” or “cttw” |
| Colour grade | One row of the price grid | The grading report |
| Clarity grade | One column of the price grid | The grading report |
| Cut grade, polish, symmetry | The largest variable usually missing from a headline price | The report. Round brilliants only, no cut grade on fancy shapes |
| Fluorescence | Discounts a stone, and can leave it looking milky | The report |
| Grading laboratory | Grades from different laboratories are not interchangeable | The report itself, verified at source |
| VAT basis | A pre-VAT number and a consumer number are not comparable | The quote, in writing, stated explicitly |
| Stone only, or stone plus setting | A setting is thousands of rand, not tens of thousands | Two separate lines in the quote |
Then run the arithmetic in this order, because doing it out of order is how people fool themselves:
- Strip the quote back to the loose stone. Setting, making and extras come out, or get priced on their own line.
- Put both quotes on the same VAT basis.
- Divide by the exact weight from the report, not the advertised weight. A “1 carat” stone weighing 1.03 gives a different rate.
- Confirm both stones sit in the same weight band and the same colour and clarity cell. If they do not, you are comparing sheets, not sellers.
- Only now compare the two per-carat numbers.
The cleanest version of this test is two quotes on the identical grading report number. When the report number matches, the diamond is a constant by definition and every rand of difference is margin. Verify any report at gia.edu/report-check and confirm the girdle inscription matches before money moves. The GIA guide explains each line, the glossary defines the terms, and the buying checklist is what to have in hand at the appointment.
Finding sellers who will give you a per-carat number at all
Before you can compare per-carat prices, someone has to publish one. Fewer sellers do than you would expect, and that fact is itself the most useful filter available to you.
Notice the asymmetry. A seller who publishes a real per-carat figure has accepted in advance that you will hold it against somebody else’s. A seller whose price arrives only after a form, a call and an appointment has arranged things so that you compare late, if at all, and usually against nothing. Neither proves anything about a specific business, but as a first sort it is hard to beat.
The practical consequence is what you type into a search box. Searching for a type of seller returns whoever bought the words. Searching the price question returns whoever is willing to answer it. So search what a carat costs rather than who sells them: diamond price per carat South Africa, diamond price South Africa, 1 carat diamond price. Then run the nine-row table above against whoever publishes a number, and ask the ones who do not why they will not.
What I do not know
- I have no verified per-carat figure for landed South African trade stock, VAT and import included, that I would defend in public. Be sceptical of anyone quoting a national trade rate without showing their sample.
- I have not verified a Rap-minus percentage for this market. The 10 to 30 percent range used above is an assumption chosen to bracket the answer, not a measurement, and the whole estimate moves if the real discount sits outside it.
- The exchange rate is the most volatile input in that estimate. At 18 rand to the dollar instead of 16.50, every figure in it rises by about nine percent. Check the rate on the day before you use the band.
- I cannot give you the magic-size step in rands. The direction is structural and certain. The magnitude depends on the cell, the shape and the week, and has to be read off the current list.
- The per-carat figures behind the trade-access inventory in the June 2026 study are not comparable to the retail figures in it, because they derive from a global wholesale feed rather than landed South African prices. That study is used here for inventory quality only. Method in the price index.
Sources and references
- Rapaport, for the structure of the price list: published weekly, quoted in hundreds of US dollars per carat, organised by shape, carat weight band, colour (D to M) and clarity (IF to I3). See rapaport.com/prices and Rapaport’s own guide to its price lists.
- My June 2026 inventory study: 230 individually listed GIA-certified natural diamonds at six South African sellers, scored against a fixed definition of premium specification, D to G colour with VS2 clarity or better. Trade-access stock 52 percent, retail-held stock 9 percent. Inventory quality only.
- My July 2026 price study: 73 rows, 71 of them carrying a price, across 18 sellers, 17 of whom are South African and one an international online retailer. Published as bands only. It is used on this page for the showroom side alone: a one carat ring in a premium South African showroom ran R105,000 to R428,000, which is a finished ring including its setting and rests on three listings of three different specifications rather than one spec priced three times. The loose-stone band above is not from this study. It is arithmetic on the published Rapaport list, as set out at the top of the page.
- Keystone and the 3 to 5 percent trade-level margin are published trade convention, not rates I have measured. The millimetre diameters are standard published reference figures for a well-proportioned round brilliant; the face-up area column and the 0.98 against 1.01 comparison are calculated from them at constant proportions.
- GIA Report Check, for verifying a grading report before you pay.
No business is named on this page, and no individual stone and price pair from the July study is published: a band across many sellers describes a market, a single weight, grade and rand figure describes one business. Prices move with the market and the exact grading, so price the stone in front of you. Method and corrections: editorial policy.
See also
- One carat diamond price South Africa. Specification at the most-asked size
- What a diamond costs in South Africa. The price, and the margin inside it
- South African diamond price index. The study behind the bands here
- Diamond size guide South Africa. Carat to millimetre, and why weight is not size
- Rapaport price list and jeweller discount. Converting a Rap-minus quote
- How wholesale diamond pricing works. The chain, layer by layer