Well i always thought that scratched sapphire or glass crystals can only be replaced until i found this stuff: Diamond polish paste!
Really useful, especially if you have a glass that is rare and hard to replace. But be aware that you also polish off all logos and stuff!
There are other sellers as well, but this one offers a complete set for a reasonable price... Takes about an hour and my fingers did hurt after it but really worth the pain. Search for "Diamantpaste" or "Diamond polish". Start with lower numbers (like 600) and work off to the highest one (12000) for perfect polished glass.
http://www.ebay.de/itm/NEU-SAPHIRGLASER ... 23165150cb