FIRST CAME CLOTHES to offer protection against the elements. Then came jewelry to give those utilitarian garments some distinction and pizazz.

Bone, wood, iron, teeth, shells and pebbles were among the preferred jewelry materials in ancient times. Then somebody discovered precious jewels and metals. And jewelry became a way of announcing one's wealth and status to the world.Not everyone, of course, could afford costly gems. So, fashion historians tell us, people started looking for a way to simulate the real thing. Voila! Costume jewelry and its classy relative, fashion jewelry, were born - and they've been growing and prospering ever since.

Among the leaders in the fashion jewelry field is Swarovski, a respected, family-owned company specializing in crystals. It was founded nearly a century ago by Daniel Swarovski, who pioneered many technological advancements, including the cutting machine.

The largest privately operated company in Austria, the firm employs 6,000 worldwide. Manufacturing takes place in the Austrian town of Wattens, where skilled craftsmen produce over 250,000 varieties of stones. The factory has the capability of cutting 30 million stones a day.

Many of the stones are sold to fashion and accessories firms that use them in their products. The parent company also has a number of subsidiaries that manufacture such diverse products as silver crystal giftware, crystal chandelier pendants, industrial grinding and cutting wheels, precision sport optical equipment and optical safety reflectors.

And then there's the latest Swarovski venture - the signature jewelry collection.

"We started it about 31/2 years ago," company representative Robert R. Sadlier explained when he visited Salt Lake City recently to present a trunk show at Nordstrom in Crossroads Plaza. "We had supplied other jewelry houses with stones for years, and finally decided to do our own settings and designs and produce our own line. It's carried now by some of the top stores in the United States, including I. Magnin, Saks and Neiman Marcus. Each season we update it a bit and add a few new pieces. But some favorites - our bow pin is one - are constant. They're classics."

The line, which includes a variety of pins, necklaces, earrings and rings, is the work of five designers and bespeaks quality and high style. Many of the designs echo those of the famous jewelers - Van Cleef, Harry Winston, David Webb and Tiffany. But when it comes to price tags, Sadlier emphasized, there's no similarity.

"We're offering beautiful jewelry that's within the reach of more people. Maybe $63 for a Chanel-like chain of crystals; $90 or so for a big pin; $325 for some spectacular pearls - the things aren't cheap, but they aren't priced like diamonds and rubies, either. You're getting a lot of quality for your money."

The quality is reflected in the lifetime guarantee that comes with each piece. If a stone drops out or a catch won't work, the company will make it right with you. Each stone, by the way, is hand set, and the backs of the jewelry pieces are just as smooth and carefully finished as the fronts. Quality also is evident in the elaborate way crystals are cut and faceted and in the brilliance of the colors - far brighter than those found in nature.

There are two basic kinds of crystal - the man-made kind that Swarovski specializes in and nature's rock crystal. Rock crystal is the common name for mineral quartz, a semi-precious stone. Man-made crystal is produced from a mixture of quartz sand, soda, potash and lead oxide, which is subjected to a high heat until molten.

Some crystals commonly sold in the United States don't contain enough lead oxide to be considered full lead and of the finest quality. Full lead crystal, noted Sadlier, has a lead oxide content of 30 percent or above, and his company puts out stones that sparkle at 32 percent.

"We take great pride in what we do," stressed the jewelry expert, who's based in New York and joined Swarovski after a stint with the firms of Miriam Haskell and Trifari. "I can tell you percentages of lead oxide and such. But just how the percentages go together and how things are mixed and made - well, those things are company secrets, and the family guards them carefully."

The company especially guards its manufacturing secrets today because crystal jewelry has become one of the hottest trends in the market, and everybody wants to get in on the action.

According to Connie Gosselin, jewelry buyer for Nordstrom stores in Utah, crystals moved to the forefront this fall when leading accessories designers began promoting them for both day and evening. Fashion magazines quickly picked up on the idea (Vogue's September cover featured all kinds of glittering jewels in wonderful rich colors). And the rush to get a king's ransom was on!

Some women, admittedly, still are a bit confused when they enter a store and see the jewelry counter alive with sparklers. They don't really understand how the day-into-evening thing works. All they can remember is Mama once cautioned them: Nice girls don't wear sparkling things before 6.

Well, Gosselin pointed out, such an attitude is as outmoded as the corset. Twinkling jewels are perfectly okay for daytime - just as long as they aren't those chandelier drops or something that clearly belongs at the cocktail party. A more tailored and subdued design is fine for the luncheon or the office - a perfect way to brighten your fashion life.

Especially important on the fashion scene right now are crystals mixed with chains and pearls. It's the look that the great fashion designer Coco Chanel popularized so many years ago - and it's playing a return engagement for fall.

Other popular trends in the jewelry market include chains interwoven with patent, suede and leather; fun fashion watches; jewelry in matte gold and silver and, of course, pins - pins in every style you can think of.

Big pins, noted Gosselin, are making a bold statement and look sensational on autumn's dramatic and more fitted jackets. Abstract and unusual shapes are everywhere at the jewelry counters. And then there are those wonderful animal pins.

"We have a whole zoo of them this season," said the jewelry buyer. "Leopards, turtles, butterflies, lizards. . . ."

Some of the stylish beasts come in metal or enamel. Others, such as those in the Swarovski collection, gleam with crystal beads. You can select the creature of your choice. And how to look after that crystal creature or other types of crystal jewelry? Here are tips from the professionals:

-Treat your jewelry with care and clean periodically to retain its sparkle.

-Warm water that contains a mild liquid cleanser is the best thing to use when cleaning jewelry.

-To dislodge dust and soap remnants, use a soft toothbrush.

-After washing, rinse the piece and dry immediately with a lint-free cloth.