Lesson 2: Using a Reticle: A Guide for Gemologists
Step 4: Gem Grading
What is a Reticle?
A reticle (réttik’l) is an optical device used in conjunction with a magnifying lens. For example, the cross hairs on a gun sight are a type of reticle. Machinists use reticles with a variety of micro-rulers and micro-protractors for fine measurements. While not specifically designed for gemology, these can serve gemologists very well.
There are two types of reticles: contact and non-contact.
- Microscope eye pieces incorporate non-contact reticles. They have the singular advantage of being always in focus and the disadvantage of being the most expensive.
- The viewer places contact reticles directly on the object being measured. These cost considerably less than the non-contact type and are available individually or in sets.
Since your needs will vary, a combination of reticles is best.