Bakelite, celluloid, Lucite and acrylic comprise a large share of the vintage jewelry market and proper care and cleaning can make the all difference when it comes to value and resale when you are talking about vintage plastics.
Michelle from Age of Plastic worked as a curator in a museum for 15 years and has some commonly accepted practices among people who handle vintage plastics on a regular basis. Some things to keep in mind:
1) Most plastics only need gentle dish detergent and warm (not hot) water. Avoid the use of solvents. If a piece has any resin wash, paint, metal hardware, or glued elements like rhinestones, keep away from water. A damp cloth or swab in the areas that are safe to clean will suffice. Sometimes it's hard to detect when a piece actually has a resin wash, so proceed with care. You might see a yellow carved Bakelite bangle with a slightly darker resin wash applied in the carved areas for contrast. This is not dirt and shouldn't be cleaned. Avoid cleaning celluloid, galalith and so-called "natural" plastics (i.e., tortoise shell, vulcanite, horn, etc.) *at all* other than wiping clear of dust, and never use solvents.
Resin Washed Bakelite
2) Bakelite can be polished with Simichrome or Turtle Wax. Simichrome is also handy for removing stubborn bits of grime on many plastics. Use the swab of your choice and a light touch. In an unrelated matter - if you test plastics, you can also use Simichrome for this. If you use 409, testing pads, or any other product, be sure to wash the tested area after so you don't strip the surface of the plastic. Never test resin washed plastics. Avoid abrasive materials and scrubbing in general, but this is of particularly little value on plastics that show scratches easily like Lucite.
3) If you purchase an item with a dealer's price sticker on it, remove with care if possible. Some plastics change color as they age and the area under the sticker will end up being lighter than the rest of the piece. On resin washed pieces this may be a judgement call, because there is always a risk of removing color along with the label. Obvious exception - original labels, which give value to a piece (like, duh, right? ;)
Fun Celluloid Pin
4) Special really important notes on celluloid: Store away from sources of heat (this is actually true for all plastics). Store out of direct sunlight. Do not let pieces come in contact with makeup or perfume. Do not store in poly bags or other closed plastic containers. Any of these things can cause a piece to become "sick" (i.e, cracked, warped, discolored). If you have a sick piece, do not store it with other pieces of celluloid, because you can contaminate them as well. Honestly, don't even buy a sick piece; they're more trouble than they're worth.