If you're describing some kind of square-ish cut, it could weigh between 1.5 and 2.0 carats, and its weight is only one quarter of what is considered when applying a value to an individual diamond.
Other considerations include its cut, its colour and its clarity.
You can pay for a gemologist's certificate to formally value your diamond.
Every diamond is valued by its cut, clarity, carat weight and colour. This measurement of 1.0 mm gives none of those details. Take your diamond to a certified gemologist who will define the four Cs for the stone, and give you an appraisal value.
304.8 mm
1.59 mm
If you have a length of 25 mm and then 12 mm it makes a length of 37 mm.
1 m is 1000 mm
Every diamond is valued according to its colour, carat weight, clarity and cut. You've offered a MM measurement, which isn't a criteria of a diamond's worth.
Every diamond is valued by its cut, clarity, carat weight and colour. This measurement of 1.0 mm gives none of those details. Take your diamond to a certified gemologist who will define the four Cs for the stone, and give you an appraisal value.
If the measurement you give -- 055 -- is converted to .55 carat, and the diamond is a round brilliant cut diamond, the diameter of the diamond at the girdle is between 5.2 MM and 5.6 MM, being the MM measurements of .50 and .60, respectively.
51.5625 mm
6 mm
A half carat diamond of this cut measures 5.2 mm at the girdle; a .65 carat diamond measures 5.6 mm at the girdle. A certified gemologist can give you the exact carat weight of your diamond.
If the diamond is a round cut, the measurement would be 7.4 mm at the girdle. If the diamond is of another cut, the measurement would be different.
First, it's not 25 mm, it's 25 ACP. Second, not very much. According to the Blue Book of Gun Values, the most it can be worth is about $50.00
A round cut diamond, cut to industry standards, that is 5.1 mm across the face of the diamond (the top) weighs half a carat.
Diamonds are usually measured in millimeters, not centimeters. Your diamond of 10 cm is equal to 100 mm in diamond measurements. The value of the diamond is whatever someone will pay you for it. However, for a diamond of this measurement, best practices dictate that you pay for a certificate from a certified gemologist, to identify its other characteristics: cut, carat weight, colour and clarity. This information will help you establish a fair value for the gemstone.
If the diamond is a round brilliant cut, this measurement at the girdle indicates that it could weigh between .20 carats (3.8 mm) and .25 carats (4.1 mm). If the diamond is of a different cut, a jeweler can remove the diamond and give you the exact carat weight.
About $50 dollars