(Timor Oriental) Timor South-East Asia DIAMOND (STRUCTURE) Jewellery
Most diamonds show a narrow absorption band at 4I55 A in the deep violet which, when seen,is diagnostic for diamond.In 'Cape' stones this is very intense, and may be accompanied by five weaker bands at 4780,4650,45I0,4350,and 4230 A in the blue and violet.Of these weaker bands the 4780 band is the
most prominent.Diamonds of the 'brown' series may show a fine line in the blue-green at 5040 A with fainter lines at 5370 and 4980 A,but these are very difficult to see.On the whole,stones showing a 'Cape'
spectrum have a blue fluorescence under ultra-violet light,while diamonds of the brown series have a green fluorescence. A blue (copper sulphate ) filter will be found to make lines in the deep violet more easy to observe. It is worth nothing that light is most easily transmitted through a diamond in the direction of the gridle. The stone should be held in this position by
tweezers or on a glass plate with the aid of a small ball of plasticine. Alterations in the absorption spectrum of diamond induced by bombardment are described in the chapter on diamond.
Most diamonds show a narrow absorption band at 4I55 A in the deep violet which, when seen,is diagnostic for diamond.In 'Cape' stones this is very intense, and may be accompanied by five weaker bands at 4780,4650,45I0,4350,and 4230 A in the blue and violet.Of these weaker bands the 4780 band is the 
most prominent.Diamonds of the 'brown' series may show a fine line in the blue-green at 5040 A with fainter lines at 5370 and 4980 A,but these are very difficult to see.On the whole,stones showing a 'Cape' spectrum have a blue fluorescence under ultra-violet light,while diamonds of the brown series have a green fluorescence. A blue (copper sulphate ) filter will be found to make lines in the deep violet more easy to observe. It is worth nothing that light is most easily transmitted through a diamond in the direction of the gridle. The stone should be held in this position by tweezers or on a glass plate with the aid of a small ball of plasticine. Alterations in the absorption spectrum of diamond induced by bombardment are described in the chapter on diamond.
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