To tell if a pearl necklace is vintage, check the drill holes (look for buildup or chipping on fakes, crisp holes on real pearls), examine for slight imperfections (perfectly round/smooth usually means fake), feel the temperature (real pearls are cool to the touch, then warm), use the tooth/pearl rub test (gritty for real, smooth for fake), and note the clasp (older styles, quality metal like 14k/gold-filled) and stringing (hand-knotted between each pearl is a good sign).
Generally, the larger, rounder, more lustrous the pearls are, and the less blemishes the pearls have, the more valuable and expensive. The only way to confidently confirm if the pearls are freshwater or saltwater would be to use X-ray techniques to determine it's chemical composition and internal structure.
Imitation pearls might have a magnetic core, but genuine pearls are made from organic material that does not respond to magnets.
Check the Clasp: A real pearl necklace will have a sturdy clasp that is securely attached to the necklace. High-quality clasps are often made from precious metals and are designed to last.
In water, pearls do not float.
The Vinegar Test
This test is again very simple: either you put a drop of vinegar on a pearl, or submerge it in vinegar. A real pearl will dissolve in vinegar or show erosion where the vinegar drop meets its surface.
The price for a real pearl necklace will range anywhere from $100 to $10,000 and more. A strand of lower quality, small Freshwater pearls, for example, will start right around $100 or so, while the highest quality Hanadama Akoya pearl strands in the largest sizes top out around $10,000 to $11,000.
If you store your pearls in airtight containers or in plastic bags, they won't be able to breathe and are more likely to dehydrate and go yellow. Store your pearls in unbleached cotton, silk, velvet, or Chamois leather. These materials retain moisture from the air, reducing the likelihood of dehydration.
The most expensive pearl colors are often deep, rich hues like Golden South Sea (especially 24k deep gold), rare Peacock Tahitian (dark green/blue/purple overtones), and intensely pink or pink-overtoned White South Sea pearls, with value heavily depending on rarity, luster, size, and lack of blemishes, rather than just the base color itself. While white and black are common, specific, saturated, and rare overtones within these categories command the highest prices.
Looking at how a piece of vintage jewelry is made can tell you a lot about its age. Older pieces often have unique ways of connecting parts, like hand-crafted clasps or hinges. The metals and gems used can also give clues. Before the 1950s, jewelers commonly used platinum and yellow gold for fine jewelry.
Before we dive right in, let's take a quick look at the basic rule when it comes to buying pearls. Always, and always buy real pearls. Fake pearls made out of glass or plastic are worth literally nothing.
It was Jackie Kennedy who said 'pearls are always appropriate,' meaning that they suit all occasions and all outfits. Indeed pearls are still worn by many brides on their wedding days and feature in most jewellers' windows today.
This is not a foolproof test because good fake pearl necklaces will have knots. Just know that real pearls will never be strung without knots.
Rub the pearls to check surface feel
Both natural and cultured pearls have textured surface due to their layered nacre structure. So when you rub the pearls lightly against each other or on your front teeth, they feel a little gritty. Fake or imitation pearls, however, usually feel smooth or glassy.
When exposed to ultraviolet (UV) light, real pearls may fluoresce or glow slightly, depending on their origin. Imitation pearls generally do not fluoresce or may exhibit an unnatural glow.
Pearl is ranked 2.5 on the Mohs hardness scale, which means it's very soft and easily scratched or abraded.
Pearls are counted by hand and then weighed with an electronic micro-balance that captures the weight in grams (mounted or strung), carats (loose), or carats and grains (loose natural). Pearls are measured using special digital calipers.
The qualities that determine the overall value of a natural or cultured pearl or a piece of pearl jewelry are size, shape, color, luster, surface quality, nacre quality, and—for jewelry with two or more pearls—matching.
For example, if you have an antique pearl necklace, then you'll want to find a GIA-certified appraiser who specializes in pearls and/or antique jewelry. To search for reputable appraisers in your local area, you can visit the American Gem Society's website.
They are considered elite gemstones and do not have a high resale value, at least as of now. Used pearl jewellery, which is sold for higher prices, is usually that which has been worn by celebrities, queens or antique pieces.