Omega Constellations of the 1950s and 60s generally featured crystals made from Hesalite, a proprietary brand of fine acrylic crystal. Hesalite is still used in preference to mineral crystal on some watches today. While saphire crystals are less likely to scratch, they shatter into tiny fragments and this can be hazardous in some environments.
Hesalite is much more prone to scratching and over the years collectors and watchmakers have come up with a bevy of home and professional remedies to buff out the scratches. Below is a sample of some of the more common techniques.
- A Fact Sheet that explains the different materials crystal are made from.
- CWR Horological pages. Good resource that includes advice about polishing crystals
- A CR4 thread, covering some interesting ways of cleaning and refurbishing
- A site offering an anti scratch cold dip formula that is claimed to create a hard optical surface that resists scratching
- An offroad thread that advocates using car polish to buff out scratches
- A Watch Report thread advocating toothpaste
- A branded polishing kit available on line
If you have perfected, or know of, a successful technique not mentioned here, let me know and I'll add it to the list.