Jewelry are items that you can buy at the Shop to instantly boost Refinement — even beyond its limit — and Love. The jewelry for sale changes randomly (necklaces, rings, etc.) and each one increases Refinement by a different amount.
After you buy a jewelry, your slave will thank you. If she also says that she has enough jewelry for any occasion, then any more jewelry that you buy will only increase Refinement by 1 regardless of what its description says. Depending on the slave's Refinement limit, this may be the only way to max it.