DATE: Art Deco, c.1920 

A fantastic colour change sapphire (synthetic) seal, with a intaglio carving to the base. It's carved with a ladies portrait and the stone changes from a bluey-purple to a turquoise-green when moved from electric light to daylight. It remains in great condition and dates to the Art Deco period, circa 1920. 

Colour change gemstones possess the ability to appear as two completely different colours depending on the type of light they're viewed under. Although daylight and electric light both appear as "white" light, the former is much richer in green wavelengths and the latter is richer in red wavelengths. When combined with a gemstone's ability to absorb specific wavelengths of light, this difference in the two light sources can be enough for certain gemstones' body colour to change entirely. Alexandrite is the best known colour-change gem, but some sapphires and some garnets can also behave in this way. 

STONES 

Synthetic Sapphire 

MEASUREMENTS 

1.4 x 1.2cm

WEIGHT 

1.8g

MARKS 

No marks present 

CONDITION 

Excellent