Below the level of gemstones sits a large trade in beads made from shell, mother-of-pearl, bone and horn — inexpensive, traditional, and widely used in malas, bracelets and ornaments. Every one of them is imitated in plastic, and because the originals are cheap, the imitations are sold with little care for accuracy. A laboratory identifies them by structure, since each organic material has an internal architecture that plastic does not.
Shell and mother-of-pearl
Mollusc shell, either the outer layers (often white, sometimes patterned) or the inner nacreous layer (mother-of-pearl), which shows the same overlapping-platelet structure and iridescence as pearl.
Identification. Under magnification, shell shows a layered, often curved structure — the growth layers of the shell — and mother-of-pearl shows the platelet texture and a soft iridescence with depth. SG 2.7–2.9. Cold to the touch. Effervesces in acid (not used). Under UV, usually inert or dull.
Plastic imitation. Uniform, warm, light (SG 1.1–1.4), often with a mould seam; "iridescence" is a surface coating without depth; drill holes are moulded rather than cut.
Dyed shell. Shell takes dye readily; bright colours are dyed. Dye concentrates in the growth layers and at the drill hole.
Bone
Usually bovine (cattle or buffalo) bone, cleaned, bleached and shaped.
Identification. Under magnification, bone shows a network of tiny dark dots or short channels — the Haversian canals that carried blood vessels — and a fine, slightly porous, fibrous texture. SG 1.7–2.0. Cool to the touch. Under UV, bone typically fluoresces a whitish or bluish colour. Bone takes dye; "antique" brown bone beads are often stained.
Plastic imitation. Uniform with no canal structure; sometimes with a printed or moulded "grain"; warm; light; seams; different UV reaction.
Ivory is a separate material (dentine, with characteristic cross-hatched "Schreger lines" in elephant ivory) and is heavily restricted in trade in most countries. A laboratory can distinguish bone from ivory under magnification, but buyers should be aware that ivory purchase and transport is illegal in many jurisdictions regardless of age.
Horn
Keratin — the same material as hair and nails — from cattle and buffalo, pressed and shaped.
Identification. Under magnification, horn shows fine, fibrous, parallel striations, often with translucent zones and a mottled colour in natural horn. Light (SG 1.3), warm, and — the classic test — a hot needle produces the smell of burnt hair (destructive; used only if necessary). Under UV, often a dull or greyish reaction.
Plastic imitation. Horn is one of the more convincingly imitated materials because plastic can be moulded with a mottled "horn" pattern; the imitation lacks the fibrous striation and gives a chemical smell under a hot needle. SG is similar to horn, which is unhelpful.
Coral, amber and jet
Covered elsewhere: Red coral (Moonga), Amber vs copal vs plastic. Jet (fossil wood) is very light, warm, takes a high polish, and is imitated by black glass (heavy, cold) and plastic.
How the laboratory identifies organic beads
Magnification is the decisive test for all of them — layered shell, canalled bone, striated horn, each unmistakable once seen. SG separates shell from everything else. UV supports. A hot needle is reserved for cases where the buyer accepts a tiny mark and nothing else has decided it. Report states the material and any dye or coating.
Frequently asked questions
Are shell beads valuable?
Generally inexpensive, unless finely carved or antique. Testing is worthwhile mainly to know what you have, or where a piece was sold as something more valuable.
How can I tell bone from plastic at home?
A loupe: bone shows tiny dark dots and channels; plastic does not. Bone is also cooler to the touch.
Is "shell pearl" a pearl?
It is a bead of shell, sometimes coated. Not a pearl. Imitation pearls.
Are bone and horn beads legal?
Cattle and buffalo bone and horn are legal everywhere. Ivory, tortoiseshell, rhino horn and some other animal materials are restricted; a laboratory can identify them but does not advise on legality.
Do organic beads need special care?
They are soft and porous; keep from water, perfume and heat, and store separately from harder beads. Organic gems are soft.