Some argue that only elephant tusks are really ivory; others accept a number of other materials, such as walrus tusks, as being ivory. There are, however, many products, such as bone and plastics, which are sometimes passed off as ivory although they are clearly not ivory.
Some of the natural substances which are substituted for elephant ivory include:
- walrus tusks – walrus ivory often has a characteristic mottling which can be brought out by moderately deep carving;
- whale teeth – often used for scrimshaw, whale teeth have a striated grain pattern;
- boar’s tusks – these are relatively small and triangular in cross section but they have a fine white colour which is popular with netsuke carvers;
- stag antlers – antlers vary in colour from yellow to brown, their longitudinal cross section shows many irregular openings. They are often used for handles of knives and daggers;
- bone – in transverse section, bone usually shows a pattern of dots, like a stubbly beard; it longitudinal section, there are usually usually brown or black streaks. Bone is not as dense as ivory and lacks ivory’s lustre;
- vegetable ivory – This is a South American nut. It is softer than ivory or bone and has an indistinct circular grain pattern.
Many types of plastic have also been used as substitutes for ivory.
Real ivory is lustrous, often with a slightly yellowish hue. Old ivory can take on a brownish patina from being handled it over the years. (Sometimes ivory is darkened using tea or other means to make it appear older than it really is. Take some saliva on your fingertip and rub the ivory. If color comes off on your finger or the area you cleaned is lighter than the rest of the item, it has been coloured to fake it’s age.)
Genuine ivory has a definite “grain,” whereas plastic is usually smooth and featureless. Pay particular attention to the butt end of the tooth, where the material can be observed in cross-section.
All elephant and mammoth ivory has parallel lines running along the length of the item. There should be circular or v-shaped lines (known as Schreger lines) perpendicular to these.
Bone has multiple darkened dots or pits. In some cases, the bone may have been bleached to hide these.
Examine the surface of the item with a magnifying glass. In genuine ivory, under 3OX magnification, very small, perfectly round air bubbles may be seen on the surface near each end, along the bottom edge and inside the tooth cavity.
Compare a known genuine ivory item in one hand with the item in question the other. The genuine item may feel cooler than the plastic one because ivory is a better conductor of heat.
Ivory is more dense than plastic, so, if two pieces are the same size, the ivory one will be heavier. (But note that the ivory may be hollow.)
Knock on the item and listen carefully. Bone and ivory sound less hollow than plastic.
Briskly rub the item with silk or flannel. Rubbing generates a static electrical charge which will be quickly dissipated on genuine ivory which is a good conductor of electricity. Plastic will readily pick up dust or small pieces of paper. If the item picks up fluff it is definitely a replica; if it doesn’t the test is not conclusive – the plastic may have been treated with anti-static chemical or water vapor in the air may have drained off the electrical charge on a plastic item.
Heat a needle red hot and touch the item with it. Real ivory is extremely dense and a poor conductor of heat and will not be marked. On bone, there will be a small dark dot and there will be a faint smell of burning hair. Plastic will melt, leaving an indentation.
Compare the item with other genuine and plastic items under long wave ultraviolet light. Genuine ivory will appear brighter (but the difference between the two is not great).
Dental x-rays may show the pulp cavity of the tooth in a genuine piece. Ordinary dental negatives are too small; the test is best performed by an oral surgeon who is equipped to handle larger sizes.
To leave absolutely no question about the composition of an item, it can be chemically tested in a forensics lab. The cellular structure of ivory is different from that of bone but lab equipment is required to definitely determine which is which.