Desktop Gem Polariscope Optical Instrument

A polariscope is used to differentiate between singly (isotropic) and doubly refractive (anisotropic) stones. A stone is placed between two polarizing filters and the top filter is then turned. If used with a conoscope, interference figures can also be seen with a polariscope.

If any questions, pls visit: ,

videos showing the use of the conoscope. )

• Stone stays dark = Single Refractive (isotropic)
• Stone stays light = AGG
  
  Anything else (blinks or snake bands), take the next step:

• Stone becomes NOTICEABLY lighter = SR- ADR
• Anything else (stays the same, gets darker) = Double Refractive

Anomalous Double Refraction (ADR) -twinkles instead of blinks. Looks like double refractive but is single refractive.

ADR is when a stone looks like it might be blinking, but really is just showing lighter where the stone is thinner or where there is a veil or weakness in the stone. Garnet and diamond sometimes display this phenomena. Tips! Be careful with using the polariscope for red / purple / orange stones. They often give confusing ADR results. Use your dicroscope or refractometer to confirm. Stones with very high RI's can also give misleading results.

Isotropic

Opal
Amber
Glass
Plastic
Diamond
Spinel
Garnet

Anisotropic

Zircon
Quartz
Beryl
Apatite
Corundum
Tourmaline
Topaz
Zoisite (Tanzanite)
Peridot
Orthoclase
Spodumene
Labradorite
Axenite
Mossenite (Syn. Diamond)