4 carat marquise diamond: size, price and what it really resells for
A 4 carat marquise diamond measures about 16.67 × 7.94 mm face-up and costs roughly $36,950–$47,875 at retail for a G colour, VS2, well-cut stone.
If you sold it, you would realistically be offered $10,500–$16,800 — about 35% of what it cost.
How big it actually looks
16.67 × 7.94 mm is the face-up measurement — what sits above the finger. The biggest apparent size per carat of any shape — over 10 mm long at 1 ct.
Carat is a measure of weight, not size, and weight rises with the cube of the diameter. That is why doubling the carat does not come close to doubling how big a stone looks: a 8 carat stone is only about 1.26 times longer than this one.
Price and the resale gap
| Retail | Resale | |
|---|---|---|
| 4 ct marquise, G / VS2 | $36,950–$47,875 | $10,500–$16,800 |
The gap is not a criticism of buying jewellery — it is simply the number nobody mentions at the counter. A jeweller's price carries rent, staff, insurance and margin, and none of that comes back to you when you sell.
What changes this figure
Colour and clarity move it most. Dropping from G to J colour and VS2 to SI2 buys a noticeably larger stone for the same money, and above about G and VS2 almost nothing you pay for is visible without a loupe. Cut is the exception and the one grade worth protecting: a badly cut diamond looks dull whatever else is true of it.
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