How to grade colored gemstones and diamonds including using the 4Cs --Color, Clarity, Cut, and Carat Weight.

Carats And Gemstone Grading

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.

clarity grading diamonds - brilliant round cut SI1
Clarity Grading Diamonds

Mastering clarity grading diamonds takes a lot of experience. This grading guide, with definitions, images, and examples, can help beginning gemologists.

clarity grading - color change sapphire
Clarity Grading for Colored Gemstones

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.

white diamonds - ring set
Color Grading White Diamonds

Mastering the art of color grading white diamonds is a challenge. Learn about the standards, terms, tools, and testing procedures and start practicing.

grading colored diamonds - the Hope Diamond
Color Grading Fancy Colored Diamonds

Fancy colored diamonds require their own color grading standards. Learn the GIA and Argyle grading systems and how to find signs of artificial coloration.

ideal round cut - traditional diamond cut grading
Traditional Diamond Cut Grading Methods

Traditional diamond cut grading methods prepare gemologists for making evaluations with minimal time, tools, and references. Learn the GIA and AGS systems.

modern diamond cut grading - cut diamond
Modern Diamond Cut Grading Methods

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 - read through test
Distinguishing Diamonds: Educating Your Eyes

Distinguishing diamonds from their look-alikes requires educated eyes. Learn what visual features to look for and the properties of many popular imitations.

gemstone cutting - fish eye
Evaluating Gemstone Cutting: The Five Ps

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.

gemstone grading - diamonds and colored gems
An Introduction to Gemstone Grading

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.

Grading Gem Carvings

Gem carvings are judged on material, workmanship, and artistry.  Learn how to apply these criteria to a piece with our step-by-step guide.

Set Gemstones - Diamonds
How To Grade Set Gemstones

Gems in jewelry settings can't be evaluated the same way as loose stones. These guidelines are for gemologists learning to grade set gemstones.

Guide to GIA's Diamond Cut Grading System

This is an explanation of the GIA's Diamond Cut Grading System complete with clear photographs demonstrating each of the grades.

gemstone value - tourmaline Tanzania
Advice for Determining Gemstone Value

Judging gemstone value is complex. New gemologists can have trouble with this. These four examples will show you how to identify the best gems.

diamond cluster - gem grading
A Consumer's Guide to Gem Grading

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.

marquis cut diamond ring - how to choose a diamond
How to Choose a Diamond

First-time gem buyers may find diamond grades confusing. Our consumer guide explains how diamonds are evaluated and gives advice on how to choose a diamond.

Common Sense Gemstone Grading - Subjective Terms
Common Sense Gemstone Grading: An Alternative System

Can gem grading avoid subjective terms? Learn about gemologist Jeff Graham's common sense gemstone grading system, an alternative to commercial approaches.

Marquise Cut Setting
Grading Fancy Shape or Fancy Cut Diamonds

A guide to grading fancy shaped diamonds, which is any diamond other than a round. Fancy shapes are cut to to obtain maximum yield from odd shaped rough.

Colored Stone Grading System

"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.

chrome tourmaline buying - fancy oval
Chrome Tourmaline Buying Guide

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.

verdelite - pear cut
Green Tourmaline (Verdelite) Buying Guide

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.

Indicolite - Brazil
Blue Tourmaline (Indicolite) Buying Guide

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.

rubellite buying guide - pendant
Rubellite Tourmaline Buying Guide

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.

Exposing Overgrading at European Gemological Laboratory (EGL)

In Sept 2014, the Rapaport Group explained that as of October 1, 2014, EGL will no longer be listed as a diamond grading report on RapNet. What it means.

diamond pendant - diamond quality grading guidelines
FTC Guidelines for Grading Diamond Quality

The FTC requires jewelers to accurately represent the diamond quality grading systems they use. Learn the guidelines and protect yourself from liability.

modern cuts - Hanneman diamond cut grading system
An Introduction to the Hanneman Diamond Cut Grading System, Lesson One

Use the Hanneman diamond cut grading system to derive the cut grade of any round brilliant with minimal measurements and calculations. Learn more here.

gold, platinum, and diamond ring - diamond grade categories
Cut Diamond Grade Categories: The Hanneman Diamond Cut Grading System, Lesson Three

The Hanneman System simplifies cut diamond grade categories. Learn how to identify the worst cut stones quickly before taking unnecessary measurements.

engagement ring - diamond proportions
Basic Diamond Proportions: The Hanneman Diamond Cut Grading System, Lesson Two

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.

diamonds - evaluating diamond cuts
Evaluating Diamond Cuts: The Hanneman Diamond Cut Grading System, Lesson Four

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.