Slocum Stone

Slocum Stone is in accordance with the provisions of CIBJO (The Gemstone Book) einzustufendes as an imitation opal material. Named after the inventor " John Slocum " this imitation is a sodium - calcium - magnesium - silicate glass, which shows a similar optical behavior of the color play of precious opal.

Slocum Stone was made in five colors - "White ", " Crystal ", " Amber ", " Semi- Black" and "Black" and 1976 of the MDI Corporation (Michigan / USA) first marketed.

In addition to the glass typical properties such as gas bubbles and streaks the most striking distinguishing feature is the marked direction dependence of the color- game-like effect. While in the supervision of the " play of color " can be clearly seen, this impression is much less pronounced in a side view.

As a clear cause for the optical effect of interference phenomena were determined on flitterartigen, ultra-thin ( 0.3 microns) and various sized flakes of aluminum foil.

Details of the procedure for the preparation of opal imitations were not known and are not patented.

Production ceased after the death of the inventor, but there are patented methods to produce similar materials.