Carat Weight and Measurement
The diamond is weighed using a very accurate electronic microbalance that captures the weight to the fifth decimal place and with the aid of gemological microscope. An optical measuring device is used to determine the diamond’s proportions, measurements and facet angles. This data is uploaded into Horizon, GIA’s operations and information management system.
The diamond is labeled with a unique internal identification number used to distinguish and track it through processing before a diamond enters the GIA Laboratory for grading. At this point, client information is removed from the diamond packaging, and the diamond proceeds to its first stop –the Weights and Measures Department.
The diamond undergoes a technical screening process to determine if it is potentially synthetic, high pressure/high temperature (HPHT) processed, or a diamond simulant. The diamond is undergoes an advanced testing for diamond identification and color origin. If further screening is required, advanced testing is performed by the Identification Services department using state-of-the-art technology such as Fourier transform infrared spectrometry (FTIR) and Raman spectroscopy to determine the item’s identity and color origin. These tests are also performed on all items submitted for colored diamond services. Bottom line, this is where it is natural and of natural color or evidence to the contrary is revealed.
A diamond may be microscopically inscribed on its girdle with its unique GIA Report Number (referred to as the GIA Inscription Registry), a personal message, or other text, symbols or logos. An inscription allows for easy identification of a diamond, a way to personalize the diamond, or serves as a form of branding for the diamond manufacturer or retailer. Gemologist uses a gemological microscope to see the microscopic inscription on the girdle of a diamond.
Every diamond is unique. Each reflects the story of its arduous journey from deep inside the earth to a cherished object of adornment. Yet all diamonds share certain features that allow us to compare and evaluate them. These features are called the 4Cs.
Although many people think of gem quality diamonds as colorless, most diamonds used in jewelry are nearly colorless with tints of yellow or brown. This can be clearly seen under a gemological microscope. Color grades are determined by comparing each diamond to a master set. Each letter grade represents a range of color and is a measure of how noticeable the color is.
Brightness is the combination of all white light reflecting from the surface and interior of a diamond. Fire is the colored flashes that can be seen in a diamond. Scintillation describes the sparkle of light you see in a diamond, and the overall pattern of bright and dark areas when you look at a diamond face-up. A polished diamond’s proportions affect its light performance, which in turn affects its beauty and overall appeal. Diamonds with good proportions optimize the interaction with light, and have good brilliance, fire, and scintillation.
Fluorescence: Many diamonds emit a visible light when exposed to ultraviolet radiation. Although fluorescence is not a factor in determining color or clarity grades, a description of its strength and color is provided on GIA Reports for identification purposes. Original article
