Depending on the cut and exact carat weight, you can purchase such a diamond today from Blue Nile and spend anywhere between US$9,500 and US$13,100.
If you already own such a stone, best practices dictate that you pay for a certificate from a certified gemologist to document this stone. Then as you try to sell it, you have the proof you need that this is indeed a valuable diamond.
Finally, anything is only 'worth' what someone will pay you for it.
The value of a flawless 0.75 carat diamond can vary greatly depending on factors such as cut quality, color, and clarity. However, as a rough estimate, you can expect to pay anywhere from $2,000 to $6,000 for a high-quality flawless 0.75 carat diamond.
A flawless stone of this size is extremely rare. Take your diamond to a certified gemologist, who will certify that the diamond is indeed flawless, and who will help you describe the stone otherwise: its colour and cut will also affect its price.
You can buy a 6.01 carat Flawless diamond today on Blue Nile, with an F colour and pay just over US$423,000.
Every diamond is valued according -- not only to its clarity and colour, as above, but must include its cut and carat weight in addition.
Your diamond may be a black diamond, if it's a diamond. There is a black diamond scale which ranks stones with AAA grades. Diamonds that are flawless are labeled IF for internally flawless, or FL for flawless. This stone could also be something other than a diamond. Only a gemologist can give you the value, based on its cut and determination of how the stone achieved its colour.
Today, on Blue Nile, you can buy a diamond -- internally flawless, not flawless (may be able to cut to flawless) -- of this approximate weight, and pay between US$456,181 and US$479,192, depending on the cut and exact carat weight that you want. A flawless diamond of this carat weight may become available at an auction house, where you could purchase it for the auction price. Without endorsement from Andwers, you can watch for such an auction, below.
Diamonds are valued by clarity -- i.e., flawless, colour, carat weight and cut. Today on Blue Nile, you can purchase a flawless diamond weighing about one carat and pay between US$2,815 and US$15,540, depending on the colour, the cut and its quality and the exact carat weight you want.
You can replace this diamond today by buying one from Blue Nile and pay less than US$1,000 for such a diamond.
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If you could buy one today from Blue Nile, you'd probably pay between US$50,000 and US$100,000 for such a stone. However, a diamond is worth whatever someone will pay you for it.
Every diamond is valued individually by its colour, cut and its excellence, and clarity in addition to its carat weight. Also, any diamond is worth whatever someone will pay you for it.
The largest Flawless, D Colour diamond for sale today on Blue Nile weighs 7.65 carats and sells for US$1,167,550 or US$152,621 per carat. (You can calculate your 10-carat estimate from this per carat value.) You may be able to find a different 'perfect' and differently coloured diamond at an auction house that weighs exactly 10 carats. The diamond could be a Deep Fancy yellow, blue, pink, or other colour. There, the price will be established by the bidders in the room at the time of sale. A deep fancy coloured diamond that is flawless and large will probably cost you more per carat than the D colour diamond, above.