Ostrowski Design X-Play Swarovski stud earrings. It's easy to see why the X-Play range is one of the best sellers in the Ostrowski Design range of jewellery. Simple yet striking, they are made from two curved squares of silver that encase a rotating Swarovski crystal. The X-Play Aurora range contains the Aurora Borealis Swarovski crystal. A clear crystal that shimmers with a range of beautiful colours to emulate the natural spectacle that is the northern lights. X-Play square measures: 15 x 15mm.