The four Cs
Carat, color, clarity and cut: what each one measures, how a lab grades it, and how much each changes the look of a stone.
Our courses are free, here on the website. Each course has short lessons built around our free tools, and ends with a quiz.
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Anatomy of a diamond
Every part of a round brilliant and every proportion on a report, rebuilt in the Cut Grading Tool.
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Reading a grading report
A diamond grading report from top to bottom, field by field, and where an IGI report differs from a GIA one.
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Diamond vs moissanite
What diamond and moissanite are, how to tell them apart with a loupe, a scale and the standard instruments, and when a stone goes to a lab.
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The history of the brilliant
Eight steps from the old single cut to a computer-designed round, the technology behind each, and what each did to the light.
The quizzes
Each course has a quiz on the whole course and a short quiz for every lesson. In a lesson quiz, the questions and the answers to pick from come in a new order every time. A multiple-choice question marks itself when you pick an answer. For the other questions, think of your answer, show our answer, and say whether you had it. At the end, you see your score and the lessons that are worth another look. Nothing is saved or sent: close the page and the quiz starts again.