For a soft blue in your designs, try these sparkling XILION rose flatbacks in Air Blue Opal. This cool-toned rhinestone has hints of warmth that cause it to live up to its opal name. Glue-on flatbacks can be applied to many different surfaces, including scrapbooks, clothing and greeting cards. Please note that when using flatbacks, you should never use a glue gun or super glue as they will damage the foil backing on the rhinestones.