Jewelry

Birth Stone Meanings

There’s a birth stone to represent those born in each of the twelve months of the year. Nearly a thousand years ago, these stones had astrological meanings. It was thought that just wearing a gemstone or a precious stone would…
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Using Chelsea Filter

The “Chelsea Colour Filter” is a dichromatic filter which transmits deep red light, ca 690 nm and yellow green light, ca 570 nm wavelengths (nanometres). It was developed (1934) in the Gem Testing Laboratory of the London Chamber of Commerce…
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