Typically it does the trick for my JLC Chrystal but I was told I should have it buffed out via machine. I was also told to use very thin sandpaper which I’m not comfortable experimenting with. I’m inclined to just leave it alone at the risk of causing damage to it. Any advice? I do enjoy a few scratches and character to the case. Wouldn’t mind a clearer view of the dial tho.
Very fine grit silicon carbide sandpaper does work. Don’t worry that you have ruined the crystal. The purpose of the sandpaper is not to remove the scratches, but to reduce the surface of the crystal down to the depth of the scratches. The crystal will be dull, but the polywatch should restore the shine of the crystal. The sandpaper shouldn’t come into contact with metal.
Wet sand with 2000 grit paper and then Polywatch. Works like a charm and no risk whatsoever. Check out this video:
What was suggested to me a few years ago was something like this and I bought a few but liked this one the best: https://www.amazon.com/gp/product/B06Y2RN3YZ/ref=oh_aui_search_asin_title?ie=UTF8&psc=1 Don't get in a hurry, don't skip any grits. Then use PolyWatch as last step. You will mostly use the rounded, end part as you approach the edge of the crystal. Painters tape on bezel/case. Have a watchmaker polish it or buy a new one if you are all thumbs and unsteady.
Like the other suggestions above, I start with a sufficiently coarse grit, and then go gradually finer. I have used powdered grit to make a slurry in the past, but currently I'm using sandpaper for the early stages and I find it less messy. If you use a slurry, you have to be incredibly meticulous to remove the previous grit before moving on to the next one. In your case, I would start with 1500- or perhaps even 1000-grit sandpaper. Cut a small strip of sandpaper no wider than your finger, so you can control it well. Go slowly and carefully and mask off the bezel with masking tape first. Don't concentrate on the scratches, but sand the crystal down evenly over the whole surface until you have removed the deepest scratches. It's not rocket surgery, just be patient. And as others have mentioned, don't panic when the crystal becomes completely opaque. Then move to a finer grit (e.g. 1000- to 1500- to 2000-grit), until you get to 2500-grit. After that you can use Novus polishing compound or Polywatch. It will take about 30 minutes and it will be beautiful. You can buy a selection of fine sandpaper grits on Amazon for $10. If you only use them to polish crystals, they will last you a lifetime.
A new crystal is fine, but the OP does have an authentic Omega crystal, and it could be original. I don't know enough about these references to say if new Omega service crystals are identical to the originals in shape.
Try Novus polishing kit, the number 3 heavy polishing paste removed a rather deep dent on my speedy crystal
Would hand polishing a scratched glass crystal with incrementally finer grit wet sandpaper work reasonably well? If not, what can one do that doesn't involve replacing the crystal or machine polishing?
Not with sandpaper no, but mineral glass can be polished with diamond paste. It often leads to poor results though as glass is only optically clean when absolutely flat and if you polish an area it no longer is. Even sapphire can be polished but again the results are often poor. Polywatch sell a kit for polishing glass.
There is polishing options that attach to a drill for sapphire crystal.... it can take some patience but they do work despite being dyi