Home >> Collecting >> Rock Collecting

How to Test Diamonds With a Black Light

Diamonds have long been prized for their beauty, investment value and rarity. Since real diamonds are expensive and hard to come by, there are many fakes on the market. These fakes can look just like real diamonds but are far less valuable. Many of them are synthetic. You can test your diamonds under ultraviolet light (also known as black light) to help determine whether they're real or synthetic.

Things You'll Need

Ultraviolet light
Another diamond or known fake for comparison, if available

Instructions

- 1
  Hold your diamond in one hand or place it in front of you. Turn on the black light and hold or place it near the diamond so the diamond is within the glow of the black light.
- 2
  Darken the room by closing the curtains and turning off the lights. If the room isn't dark enough, take the diamond and black light into a closet or small, windowless room and close the door.
- 3
  View the diamond closely. It will most likely have a faint blue glow if it's a real diamond; however, the better the quality, the less blue light will be visible. Fake diamonds or cubic zirconia will usually not glow blue.
- 4
  Compare the glow from your diamond to another diamond, if you have one, that you know is real. You could also compare the glow of the diamond to a known fake or cubic zirconia.

Rock Collecting