Some of the rarest diamonds in the world originate from Western Australia's Argyle diamond mine, which is currently preparing for closure after 37 years of operation.
Many coloured diamonds from Argyle were sold with a certificate issued by Argyle Diamonds, however depending on the year and size of the stone, it may have failed to qualify for laser inscription and certification by the company. Over the years the minimum size of diamond provided with a laser inscription and certificate has been reducing. In 2005 the minimum size was 0.20 ct, which decreased to 0.15 ct in 2009 and since 2016 it has been 0.08 ct. For some owners, a certificate has been lost.
Without a certificate of origin, a diamond from Argyle will not be maximising its value, which depending on the market, can attracted a premium of typically 15 – 25%. The main factors determining the price of a diamond are Carat, Colour, Clarity and Cut – the traditional 4Cs. However in the case of coloured diamonds from Argyle, the origin is also a key price factor and for that certification of origin is imperative – a 5th C.