Rare diamond fails inspection

Better a diamond with a flaw than a pebble without, the saying goes.

It is a particularly apt line for a rare pink diamond unearthed at Rio Tinto’s Argyle mine in February that was initially thought to be among the biggest and most valuable such gems in the world.

The 12.76-carat sparkler — on weight alone estimated to be worth $12 million — is now destined to be a Melbourne museum piece after cutting and polishing magnified a series of internal flaws, which are common to the fickle pink stones, rendering it less valuable.

Rio has tried to turn its disappointment into a virtue, by donating the now 8-carat stone to Museum Victoria.

It is understood the diamond had one major internal fault line that could not be overcome. So rather than risk the stone, Rio decided against further cutting.

Robin Hirst, from Museum Victoria, said Rio had a tradition of donating diamonds to the museum and it was remarkable to have an (important piece of Australian mining history.

Leading Sydney pink diamond jeweller Michael Neuman said that the stone was still very valuable, as it retained its status as the largest pink diamond found in Australia, and Rio’s move was “an incredibly generous gift to the nation”.