Gem-A Education: How to use the refractometer
4:36
Gem-A education: How to use the London dichroscope
11:46
How do you KNOW what a gem is? [Refractometer Tutorial]
6:11
🌟 -- How to Use a Refractometer (Abbe)
5:28
How to Classify a Lead Glass–Filled Ruby by GIA
15:18
WHAT'S REALLY IN YOUR FOOD? How to Use a BRIX Meter
15:08
Unboxing a Gemologist's Spectroscope
9:47
Gem Identification - Refractometer Basic Use
4:56