How much would a 1.5 carat blue diamond cost?

14 Million

Another Answer

Natural blue diamonds are among the most rare of diamonds. First, you'd have to locate such a stone. Given its rarity, you would probably pay whatever the seller asked in terms of a price.

(Today at Blue Nile -- where there are no blue diamonds listed -- you can buy a rare 1.4 carat Fancy Vivid Purplish Pink radiant-cut diamond for US$385,0000. A blue diamond with similar qualities would cost you more, again, if you could find one.)