(IDEX Online) - The initial offering of the world's first fungible diamond commodity offering - a sealed plastic coin of around 4.5 carats - was 50 per cent over-subscribed, says the company that launched them.New York-based Diamond Standard says it has sold the first batch of 5,000 coins to investors, and will now make a further $50m of coins available.Each coin (pictured) contains "a set of certified natural diamonds with identical geological scarcity" across a wide range - D to L color, flawless to SI2 clarity, VG to EX GIA cut scale, from 0.21-carats to 0.75-carats.The coins are traded as the first regulator-approved diamond commodity and their price fluctuates. The second offering of coins is capped at $50m. Those sold in the first of five $10m series will be priced at $5,750. Subsequent series will be priced according to prevailing diamond values.