How to tell the difference between dichro and super finely crushed opal. Home › Frequently Asked Questions (FAQ) › Information › How to tell the difference between dichro and supe.... Posted by Steve K on April 13, 2023 Dichro is metal, it will stretch on the glass differently. Opal is a small additive stone, it will sporadically lie in the glass. Dichor also has more of one color that can fade. Opal will change color at angles.