A diamond's value is based on its carat weight, its cut, its clarity and its colour. A local jeweler may be able to answer your question given an individual stone.
The answer assumes you mean a ~25.00 carat stone and not a .25 carat stone.Today's search for loose diamonds produced this result:A round stone of 27.12 carats, with a J colour, I1, without a certificate and graded as 'excellent' cut. It is priced at US$576,249.00.
"The market value for natural blue diamonds is very high. They are very rare and highly sought. The average price for a one carat blue diamond may be as high as $150,000."
Half a carat is .50, and a quarter of a carat is .25, therefore 3/8ths of a carat is .375
Around 25 - 45 dollars.
Diamond of 2 carats (jewelry grade) can be worth 1,000 to 20,000 dollars more or less. Industrial grade diamonds: From experience, about 25 years ago I saw a 40 carat industrial grade diamond valued at $4,000, $100 dollars a carat. It looked like a dirty piece of quartz.
If you mean 1/4 carat, that is one quarter of a carat or 25 points (one carat = 100 points) .
24 is the highest carat of gold, which is about 99.999% pure.
A 25 carat diamond will be difficult to find, since that size of stone is larger than most diamond merchants have on hand. For comparison, however, the link below shows the auction price of a 35+ carat stone, which sold for over US$24 million.
A .25 carat round GIA certified diamond in F color and VVS2 clarity costs about $590 and a .25 carat princess diamond in E color and VVS1 clarity costs $510.
25 out of 45 = 56% = Failing grade
About 3.5$ mil.added 11/3/2010Not exactly true.A standard ounce of is 141.747 carats.Industrial diamonds can sell for $1-$5 per carat .Jewelry grade diamonds can cost $50 per carat for the smallest diamonds to $2000-$10,000 for a nice white 1 carat diamond to $25 million for a 50 carat diamond. ( diamond over 20 carats are generally considered semi unique and hard to price)So given that range an ounce of diamonds can cost from about $150 up to $300,000,000. In addition since a single 141.47 carat diamond would be one of the largest diamonds in the world, it could be priceless
1580.75 USD