Grading Gemstones and Diamonds
How to grade colored gemstones and diamonds including using the 4Cs --Color, Clarity, Cut, and Carat Weight.
Carats are the units used to measure gem weight and one of the main factors in gem grading. Learn what affects the value per carat of various gem species.
Mastering clarity grading diamonds takes a lot of experience. This grading guide, with definitions, images, and examples, can help beginning gemologists.
Many factors contribute to a colored gemstone's clarity, and how you discuss it can affect your sales. Learn how gemologists conduct clarity grading tests.
Mastering the art of color grading white diamonds is a challenge. Learn about the standards, terms, tools, and testing procedures and start practicing.
Fancy colored diamonds require their own color grading standards. Learn the GIA and Argyle grading systems and how to find signs of artificial coloration.
Traditional diamond cut grading methods prepare gemologists for making evaluations with minimal time, tools, and references. Learn the GIA and AGS systems.
The GIA modern diamond cut grading method is the most widely accepted in the industry. This step-by-step guide covers the tools and techniques you'll need.
Distinguishing diamonds from their lookalikes requires educated eyes. Learn what visual features to look for and the properties of many popular imitations.
Of the Four Cs of gem grading, only the cut is something a faceter can control. Learn how to evaluate gemstone cutting accurately with the Five Ps system.
There were no standards for grading gems 'til the 30's. Then the G.I.A. instituted the Four C's method for diamonds, which has now become the standard.
Gem carvings are judged on material, workmanship, and artistry. Learn how to apply these criteria to a piece with our step-by-step guide.
Gems in jewelry settings can't be evaluated the same way as loose stones. These guidelines are for gemologists learning to grade set gemstones.
This is an explanation of the GIA's Diamond Cut Grading System complete with clear photographs demonstrating each of the grades.
Judging gemstone value is complex. New gemologists can have trouble with this. These four examples will show you how to identify the best gems.
Learn how gemologists evaluate color, clarity, cut, and carat for gem grading. Consumers can use this information to find the right stone for their needs.
First-time gem buyers may not understand how choosing, rating, and grading diamonds work. Our complete guide explains and offers advice on all three.
Can gem grading avoid subjective terms? Learn about gemologist Jeff Graham's common sense gemstone grading system, an alternative to commercial approaches.
Fancy cut diamonds can have any finished shape, except round. These stones have their own grading criteria, in particular regarding proportion and symmetry.
"Just Ask Jeff" shares his thoughts on the Color Stone Grading System of The GIA. In May 2008, he had been informed that the grading system was modified.
Our chrome tourmaline buying guide can help you learn how these gems are graded, what to avoid, and how to identify a high quality stone.
Our verdelite buying guide can help you learn how verdelites are graded, what to avoid, and how to identify a high quality stone or a bargain in the rough.
Our indicolite buying guide can help you learn how these blue tourmalines are graded, what to avoid, and how to identify a high quality stone.
Our rubellite buying guide can help you learn how rubellites are graded, what to avoid, and how to identify a high quality stone or a bargain in the rough.
The effects of the 2014 scandal over diamond overgrading at EGL labs are still emerging. Learn what gemologists and retailers can do to prevent overgrading.
The FTC requires jewelers to accurately represent the diamond quality grading systems they use. Learn the guidelines and protect yourself from liability.
Use the Hanneman diamond cut grading system to derive the cut grade of any round brilliant with minimal measurements and calculations. Learn more here.
The Hanneman System simplifies cut diamond grade categories. Learn how to identify the worst cut stones quickly before taking unnecessary measurements.
In the Hanneman cut grading system, you must consider diamond proportions to grade a round brilliant stone. Learn what they are and how to calculate them.
The Hanneman System makes evaluating diamond cuts easier. You can use total height and C/P ratios to cut grade round brilliants without subjective terms.
The US Federal Trade Commission (FTC) can help jewelry marketers avoid making deceptive claims. Learn about the FTC diamond jewelry guide updates for 2018.