Castiglione Jewelers is a direct importer of GIA & EGL certified natural loose diamonds. Castiglione Jewelers ' extensive diamond collection consists of all the popular shapes in various sizes.


A diamond grading report from the Gemological Institute of America (GIA) or from the European Gemological Laboratory (EGL) will accompany each of our loose diamonds.

These laboratories are recognized around the world as the finest in gemological education and grading. Each grading report not only lists the exact measurements and specifications of an individual diamond, it also evaluates the diamond based on The Four C's.


Established in 1931, the Gemological Institute of America is the world's foremost authority on diamonds. GIA exists to protect all purchasers of diamonds and is the industry standard used to accurately and objectively determine diamond quality.


EGL USA is one of the world's premier independent gemological laboratories. For over 25 years it has offered the fine jewelry trade and consumers accurate, reliable diamond identification and professional certification to validate their diamond purchases.


The Four C's of a Diamond

A diamond's most important attributes are its cut, color, clarity, and carat weight: The Four C's of a diamond.

When a diamond is cut to ideal proportions, light will reflect from one mirror like facet to another and disperse through the top of the stone, resulting in a brilliant display. Diamonds that are cut too shallow or deep will lose light through the sides and bottom of the stone and may have a darker center.



The color of a diamond is graded on a scale from D to Z. Truly colorless stones are given a D grading and are extremely rare. Although colorless stones are more valuable than faintly yellow colored stones, diamonds with intense yellow, blue, pink, or other colors are also extremely rare and valuable.



Clarity is graded on a tiered scale beginning at flawless (F) followed by internally flawless (IF), then to VVS1 and VVS2 (very very slight inclusions), VS1 and VS2 (very slight inclusions), SI1 and SI2 (slight inclusions), and finally I1, I2 and I3 (inclusions are visible to the naked eye).

Virtually all diamonds have some inclusions or flaws. The difference in the clarity of a stone depends both on its appearance to the naked eye as well as the detail seen through a microscope. The location of the flaws are also important.

The carat is a unit of weight derived thousands of years ago from the relatively constant weight of the carob seed. Carats are divided into 100 points. The carat weight is the size of the stone and has no bearing on the color and clarity of a diamond.