Once in a Blue Moon, a sale of blue diamond’s collection will be conducted in Hong Kong, Tokyo and Perth, Australia. It will be held few days prior to the bids closing on April 8, according to a release from Rio Tinto who is all set to showcase the collection of rare diamonds like blue moon.

Rio Tinto's Argyle Diamond Mine which is well known in Australia for producing rare diamonds like champagne and pink color diamonds.  According to the sources, "Once in a Blue Moon" is Rio Tinto's first collection of blue and violet diamonds, which are rarely found in nature.

"We are excited to showcase our first-ever collection of precious blue and violet Argyle diamonds, sourced from several years of production at the mine. It is an enchanting collection that will appeal to connoisseurs and collectors alike, “Argyle Pink Diamonds Sales and Marketing Manager Josephine Archer said.

The “Once in a Blue Moon” will showcase a collection of smaller diamonds, a range of premium and commercial diamonds and features single cuts and a number of matching pairs, according to the release.
Argyle mine has just 10 years of production left , and only a sporadic occurrence of blue diamonds, Rio Tinto expects the "Once in a Blue Moon" collection to attract considerable attention, both in Australia and overseas.

Rio Tinto is expecting the show to attract considerable attention both in Australia and overseas. Rio Tinto has only 10 years of production left for the Argyle mine and only periodic appearance of blue diamonds.