I suffered an abrasion on the mineral glass crystal of my nice titanium chronograph watch. It looked unsightly... not bad enough to compromise water resistance, but it just annoyed me. Before sending it off for a new crystal, I decided to ask around to see if there might be some way to polish out the blemish.
Sure enough, someone suggested toothpaste. Toothpaste??
I thought that was nuts. That is, until I tried it.
First I experimented on an old clunky watch that has a scuffed crystal. The scratch actually diminished after a few rubbings of toothpaste (with whitener) with my finger. So, I decided it was time to try it out on my pricier titanium chronograph watch.
Well, low and behold the toothpaste worked! I examined the crystal under a loupe and found a few very small short hairline scratches left behind, but the big blemish was gone. With the naked eye, the crystal looked nearly perfect. Before hand, I tried scratching out the blemish with my fingernail to no avail. Examining the crystal up close sure looked like it glass had suffered a material loss. Maybe it was just heavily impacted debris?
In any case, it's worth a shot--if you've got a scratched crystal, try a good hard toothpaste rubbing before seeking professional repair. It just might save you a bit of money.