When some people talk about holiday sparkle, they mean the glitter glow of gems and jewels. More fine jewelry is purchased in December than at any other time of year. Fine jewelry is a possession designed and crafted to last a lifetime. The proper care will assure this lasting quality.

Jewelers of America, a trade association, offers these tips on the care of fine jewelry:DIAMONDS:

Even though you wear your diamond engagement ring 24 hours a day, you should still give a thought to its care:

- Don't wear it when you are doing rough work. Even though a diamond is durable, it can be chipped by a hard blow.

- Don't let your diamond come in contact with chlorine bleach when you are doing household chores. It can pit and discolor the mounting.

- Do see your jeweler at least once a year and have him check your ring and other precious pieces for loose prongs and wear of mountings. He can give them a professional polish, too.

- When not wearing your diamonds, keep them in a fabric-lined jewel case or a box with compartments or wrap each piece individually in tissue paper. Don't jumble diamond pieces in a drawer or jewelry case, because diamonds can scratch other jewelry or each other.

- Diamonds get smudged and soiled and dusty. Lotions, powders, soaps, even the natural skin oils, put a film on diamonds and cut down their brilliance. You can clean your diamonds by using a small bowl of warm suds with any of the mild liquid detergents used in the home. Brush pieces with a eyebrow brush while they are in the suds. Transfer to a wire tea strainer and rinse them under running water. Pat dry with a soft, lintless cloth. Liquid jewelry cleaning kits are also available.

KARAT GOLD JEWELRY:

- Always separate your gold jewelry in a compartmentalized jewel box to protect against scratching.

- Remove all jewelry before showering or cleaning. Soap can cause a film to form on karat gold jewelry, making it appear dull and dingy. By preventing the formation of this film, you immediately reduce the occasions your pieces will need to be cleaned.

- Many commercial cleaners are available for cleaning jewelry at home. Ask your jeweler for recommendations. In addition, a soft chamois cloth is an effective and inexpensive way to keep pieces lustrous and shining.

- Grease can be removed from karat gold jewelry by dipping the jewelry into plain rubbing alcohol.

- Remove jewelry when applying makeup and face powder. Wash hands after applying makeup and before putting on jewelry.

- Keep jewelry in a dry place.

CULTURED PEARLS:

- Put pearls on after applying cosmetics, hair sprays and perfumes.

- Place cultured pearl jewelry in a chamois bag or wrap them in tissue when putting them away. Don't toss them carelessly into a purse or jewel box where they can be scratched by hard metal edges or harder stones.

- Bring your pearls back to your jeweler for restringing once a year. Cosmetics and ordinary wear weaken and stretch the threads on which the pearls are strung. It's better to be safe than sorry.

- Have pearls strung with a knot between each pearl. This will prevent loss of pearls if the string should break.

- Don't clean cultured pearls with chemicals or abrasives.

- Wash them with mild soap and water after taking them off. This will remove all traces of perfume, cosmetics or hair spray from the pearls.

FINE WATCHES:

- A mechanical watch should be checked regularly by your jeweler and serviced according to manufacturer's suggestions. This is important because tiny particles of dust can get into the works, increasing friction of moving parts.

- Wind your watch in a clockwise direction, preferably about the same time each day.

- Although many watches are equipped with shock-resistance devices, it's not wise to subject them to overly vigorous treatment.

- Replace broken or scratched crystals immediately. Even a hairline crack can let dust or moisture into the mechanism, threatening its accuracy.

- Unless the degree of water-resistance is clearly spelled out, don't risk wearing it into the shower or pool, or on a moist wrist.

- No matter how handy you are, don't attempt any do-it-yourself watch repairs. Only an expert should be trusted to put your watch back into working condition if there is a problem.

- It's best to replace a quartz battery in a quartz watch before it runs out. Dead batteries left in the watch can leak or corrode and ruin it. Also, don't attempt to change the battery in a watch yourself. Batteries run for about two years. Those in less expensive, multifunction digitals have shorter lives, as little as six months, if the wearer frequently uses extra features such as calculator or game.

COLORED GEMSTONES:

There are many different types of colored gemstones, some of which require specific care and cleaning procedures. Ask your jeweler for specific instructions for your particular colored gemstone.