← All tools
Gemological tool

Chelsea Filter

Quick chromium test, key for emeralds and rubies

Typical price$ 20 - 80
PortabilityHighly portable
Field noteCredit card size

How to use it

  1. Hold the Chelsea filter directly in front of your eye
  2. Hold the stone under incandescent or halogen light (NOT fluorescent or LED)
  3. Look at the stone through the filter
  4. Note whether the stone appears red/pink or green