I received an e-mail with a rather perfunctory heading ("Why not?"), no salutation, that question and the signature "cz". As Countess Cora Crowley said, during a tiff with the Earl, "I shall not address the tone of your remark", but I shall deal with the substance.
The pearl oyster and freshwater pearl mussel produce and deposit nacre on the shell (called 'mother of pearl') and on the pearl. (For a more detailed definition of nacre, see here.) The successive, overlapping layers of nacre give pearls their lustre. Lustre refers to both brilliance (how the surface reflects light) and glow (how the layers of nacre refract and diffract light). Thick nacre doesn't guarantee high lustre; lustre depends on the pattern of nacre, but thick nacre is far more desirable than thin.
The best pearls also display orient, defined by Professor Barbara W. Smigel as "a delicate, shifting, iridescent color layer that is distinct from the basic body color of the pearl or from its lustre... Although most pearls have that characteristic 'pearly luster', only fine quality pearls have orient."
Imitation pearls are made from a shell or glass bead coated with a solution containing fish scales or other iridescent material. They will never have a fine pearl's lustre and depth, and their iridescence (should they have any), is like poly satin compared to silk charmeuse. Fakes are usually "too-too": too perfectly matched, too round, too sharply lustrous. The overall effect is like being hit by high-beam lights, and about as soulful.
Expect to pay more for genuine pearls, but thanks to advances in pearl farming, there is not as wide a gap as you'd think.
A pair of good quality fakes, Majorica 8mm round white pearl studs; price, $55 at Sak's.
A pair of 8-9mm round white freshwater pearl studs from Pearl Paradise; price, $115. You can see the difference, no?
Once you decide to wear genuine pearls, read, look and follow your taste. For me, orient trumps roundness, and perfectly smooth surfaces are not my first criterion.
I avoid pearls dyed any colour not found in nature, and am wary of that enhancement even if the dyed pearl is "pearl coloured", because dyes can eventually mottle a pearl or fade. If it's not terribly pricey and you love that dyed colour, go ahead. Jewelers will swear the dye is stable, but it's done at the farm, not by them, so how do they know what will happen in 10 years?
Fakes range in quality, from the intended-to-fool-no-one $25 gumballs at H&M to the $250 "South Sea" strand, below by Magnificent Costume Jewels—and up, once a designer name is attached.
I could choose a superb South Sea strand for comparison, and you'd faint at the price and there goes my case. But I, living a casual (and financially disciplined) life, would be thrilled in the freshwater strand of large assorted drop pearls (price, $846) from Kojima Company:
A pendant of one spectacular pearl is far more charismatic than a necklace of fakes, or the bleached, banal whites I see at department store counters and even brand jewelers.
A golden South Sea Pearl pendant (chain not included); set in rhodium plate (over silver) price, $153, from Kojima Company:
Warmed by your skin, lighting your face, genuine pearls simply have no equal. Fakes have a place, but if you can try on the real thing, "cz", I'm betting you'll see the difference.