Now at Costco: A $1M Diamond Ring And that's apparently a discount By Kevin Spak, Newser Staff Posted Apr 8, 2011 11:57 AM CDT 2 comments Comments This image from Costco's page shows their $1,000,000 diamond ring. (Costco) (Newser) – Finally, Costco is catering to its multi-millionaire clientele. The discount retailer is now selling a 6.77 ct diamond ring for a million bucks, the Consumerist reports. Costco has sold some high-end diamond jewelry in the past, starting with a $180,000 ring in 2005, but a million is quite the step up, the blog notes. And while it might seem out of place at a store known for bulk-priced groceries, it is a discount; Costco lists the ring’s IGI value at $1,601,875.