Step 3: Practical Gemology

Lesson 29

If you’ve missed it, try taking this sample gem identification quiz, too.

Examining a Rough Gemstone: Quiz 1

You’ve received a piece of rough to identify. First, you clean it carefully. Next, you give it a thorough visual exam, using your unaided eyes, a loupe, and a microscope. In the process, you note the following bits of visual information.

1. What optical feature do you see here?

color zoning

2. What physical feature do you see here?

conchoidal fractures

3. In the following picture, what inclusions do you find?

red rutile needles

4. What kind of inclusions can you see in the following picture?

negative crystals - gemstone visual examination

Rough Gemstone Visual Examination Advice

Some people have difficulty determining the identity of rough material. Although the process is the same for identifying cut material, you often won’t have a refractive index reading to guide you. However, you’ll still usually gather enough information with which to work.

Find a Place to Start

Look at the rough pictured in Question 1 again. All but the most novice gemologists know that purple coloring and strong zoning are common to amethyst. While this piece certainly looks like an amethyst (a quartz variety), you…