Golf-Ball Sized Diamond Needs a Pro's Evaluation

Well, it wasn’t as big as the 1,100+ carat tennis ball-sized diamond we reported on in October, but the latest gem find announced by Sierra Leone’s Minerals Agency is a 476-carat diamond that is bigger than a golf ball. The diamond was discovered in an area spanning from the Kamara Gbense to the Tankoro chiefdoms in Sierra Leone (Kono District).

According to a press release by Trustco Group Holdings, “an initial assessment indicates that this find is the 29th largest diamond ever discovered. Any value indication of the diamond is pure speculation at this stage as the diamond has not yet been examined and assessed by the necessary experts. It is Meya’s intention to sell the diamond through an international auction. Images of this unique diamond can be viewed on Trustco’s website and more information is provided on www.informante.web.na.” Meya Mining is the Trustco subsidiary that unearthed the special rock.

The genuineness of a diamond the size of a golf ball will of course be put into question. Diamonds are unique among gemstones because they are composed of a single element (carbon), while virtually all other gems contain multiple elements including significant amounts of oxides There are technologies that can help confirm or deny the authenticity. As we mentioned in a previous article, 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.

Before the diamond is valued, it will be analyzed and scrutinized by authorities in the diamond industry. Real diamonds are formed in the earth over the course of thousands of years, under crushing pressures and intense heat. Synthetic stones, however, include high-pressure high-temperature (HPHT) diamonds and laboratory-grown diamonds formed by Chemical Vapor Deposition (CVD), techniques which produce products nearly indistinguishable from natural diamonds.

Fourier Transform infrared (FTIR) spectroscopy can be used to analyze the impurities in diamonds to help confirm if the diamond is synthetic or if it has been treated. It can be a useful tool to determine whether diamonds are natural. FT-IR spectroscopy produces an infrared absorption spectrum that represents a ﬁngerprint of the sample with absorption peaks which correspond to the frequencies of vibrations between the bonds of the atoms making up the material. Because each element is a unique combination of atoms, no two compounds produce the exact same infrared spectrum. (Read more about synthetics diamonds here.)

After the genuineness is confirmed, I imagine the 4 C’s of diamond quality will be applied, if they haven’t already.

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.

You can see a video of how a GEM Certification & Assurance Lab does expert authentication and quality grading certification of diamonds.

Read Analysis of Diamonds by FT-IR Spectroscopy to learn more techniques that provide a rapid, reliable information source of great importance to classifying gemstones.