Gold Coast 1921-24 15s dull purple and green Specimen, SG100asGold Coast 1921 24 15s dull purple and green, script watermark, die II, overprint SPECIMEN, SG100as. A fine mint example with part original gum. A very good example despite a couple of tiny marks on the gum and minor traces of rubbing, which is commonly seen and does not detract from overall quality. "SPECIMEN" examples were used solely by postal administrations for reference purposes to help spot any attempted forgeries. The Stanley Gibbons catalogue