Did you ever wonder how those mined chains of carbon atoms that have crystallized become the stars of engagement rings, necklaces, bracelets and even crowns? They were formed in the earth over the course of thousands of years, under crushing pressures and intense heat, and yet they have emerged as showcase pieces in jewelry stores. After the diamond-bearing ore is crushed and processed, the rough diamonds are sorted into three categories: gem quality, industrial quality, and boart (used as an abrasive in cutting tools). The gem-quality diamonds are then classified, and valued, according to the 4 C’s of diamond quality. This accredited gem certification and assurance laboratory shows how those 4 C’s are determined:
- Carat: Weight: Precise measurement of carat weight using electronic balances to a thousandth of a carat and then measured with an optical scanning device that creates a diagram of every facet and angle.
- Color: Color is graded on a scale from D to Z with each letter representing a slightly more saturated color. Diamonds are examined in a standard lighting environment and are compared to a set of precision master color diamonds. It takes an expert eye rather than technology to grade the color. The diamonds are also checked for fluorescence, which is a permanent identifying characteristic of the diamond.
- Clarity: Clarity is graded by examining the diamond under a microcope to assess internal and external characteristics such as crystals and feathers. Gemologists also note inclusions, including the number, type, position and relief. A 10X loupe is also used to view the diamond in several different positions.
- Cut: A light performance analysis system can assess and capture an image of the diamond’s optical brilliance and optical symmetry.
Although portable X-Ray Fluorescence cannot measure carbon, the technology can be deployed to measure Zr, and thus, to distinguish between the diamond look-alike, cubic zirconia, and real diamonds. In addition, the non-destructive technology can be used to analyze the composition of any metal-based jewelry. And what happens to those diamonds that do not meet gem-quality standards for color, clarity, size, or shape? They are used principally as an abrasive, and are termed “industrial diamond.” They may not be as ‘pretty’ or ‘brilliant’ but industrial diamonds have proven to be more cost effective in numerous industrial processes because they cut faster and last longer than any rival material. The U.S. Geological Survey declares diamonds “may well be the world’s most versatile engineering material as well as its most famous gemstone.” And maybe even a girl’s best friend.* View The Journey of your Diamond’s GCAL Process video. *Marilyn Monroe’s birthday: June 1st
Hello.
While it is true that diamonds are formed under “crushing pressure”. It is not under “intense heat”. Diamonds are formed deep in the Earth’s crust where the geothermal gradient is relatively cool. That is why diamondiferous kimberlite host-rocks are associated with cratons like the Kapvaal craton in South Africa, the Slave craton in Canada and the Siberian craton in Russia. Intense heat destroys diamonds.
Cheers…. Ben Whiting, P.Geo.
Thank you for your comment, Ben. Yes, I can see where the confusion might have come from and to your point, diamonds don’t need that much heat to form naturally. However, in order to make synthetic diamonds, temperatures around 1,400-1,500C are typically required. We appreciate your clarification.
Jonathan Margalit, PhD
Business Development Manager – Precious Metals & Regulatory
Thermo Scientific Portable Analytical Instruments