It's everywhere. You see it at yard sales, rummage sales, estate sales, thrift shops, consignment stores, and online - vintage costume jewelry.
Unlike fine jewelry made of precious metals (karated gold, sterling silver, platinum, etc.) and precious and semi-precious stones (diamonds, rubies, emeralds, topaz, etc.), costume jewelry is usually manufactured from less valuable materials like plastic, glass, wood, and plated base metals. Made not to be investments, but as fashion "accessories," costume jewelry is often considered "disposable."
And that's why vintage costume jewelry is so collectible! Some of the most desirable pieces - Bakelite, Art Deco, Chanel - can command thousands of dollars in the secondary markets because so little has survived relative to the demands of collectors.
But it needn't cost you an arm and a leg to acquire a collection. Many if not most specimens sell for just a few dollars up to $300. But (and this is most important) know your subject. As with any collectible, a little knowledge could help you avoid paying too much for a common piece, or missing out on a yard sale "find" worth hundreds.
Costume jewelry has been around since at least the 18th Century, so it is important to be able to distinguish the different design periods as some, like Art Deco and Art Nouveau, are presently more collectible than others.
A good piece of costume jewelry is not always signed. Many design houses such as Monet and Trifari stamp their names or marks into every piece, but some designers either failed to do so early on, or never did.
Condition is everything! Chip, cracks, and missing pieces will seriously diminish the value of even relatively rare specimens. An example of what to avoid: Rhinestones that have lost their glitter. Rhinestones are lead-glass crystals that usually have a foil back to help reflect light. If exposed to excessive moisture, the foil will darken and cannot be restored. If you must have the piece, you will have to have the damaged Rhinestones replaced. (Fast fact: Rhinestones are sometimes referred to as "paste" or "diamente.")
Finally, personal taste and experience should be your guide in what to collect. Always buy what you like. You will have to live with it or wear it, and there's no sense in purchasing something you can't get excited about, unless, of course, you know that it's worth a lot of money. Then you can turn around and resell it!
Experience (and a good magnifying glass or jeweler's loupe) will help you judge whether a piece is worthwhile or not. Is it well made? Is it plastic or is it Bakelite? Is it signed? Has it been repaired? Is the design crude or well-done? Are they common Rhinestones or Swarovski crystals? (Swarovski crystals, with their high lead content, and coatings instead of foil backing, are considered the best quality Rhinestones.)
Interested in unearthing more information about this popular collectible? The following resources are good places to start.
"Collecting Costume Jewelry 101: The Basics of Starting, Building and Upgrading (Identification & Value Guide)," by Julia C. Carroll
"Collecting Costume Jewelry 202: The Basics of Dating Jewelry," by Julia C. Carroll
"Inside the Jewelry Box: A Collector's Guide To Costume Jewelry, Identification And Values," by Ann Mitchell Pitman
"Inside the Jewelry Box, Vol. 2: A Collector's Guide to Costume Jewelry: Identification and Values," by Ann Mitchell Pitman
"Unsigned Beauties of Costume Jewelry: Identification and Values," by Marcia Sparkles Brown
"Warman's Costume Jewelry Figurals: Identification and Price Guide," by Kathy Flood
American Society of Jewelry Historians
Check out their glossary of jewelry terminology and the News & Events section.
Characteristics of Costume Jewelry
This Suite101.com article by jewelry designer Marie Loughran describes the difference between Fine, Bridge, and Costume jewelry.
Eclectic Vintage Costume Jewelry and Collectibles
PictureTrail links to information on various sites.
Great site, lots of pics/info: company/designer histories, tips on caring for jewelry, patents, links, more! Caveat: best navigated from Site Map!
Vintage Costume Jewelry History--Designers
For a fascinating introduction to vintage costume jewelry designers, check out this video offering on YouTube.
Vintage Fashion and Costume Jewelry Club
Club hosts conventions, publishes quarterly newsletter.