This is the name given to the more-or-less yellow variety of corundum, in accordance with modern terminology for colors other than blue and red. It was also formerly known as “oriental topaz."
Appearance -Yellow sapphire may occur in quite a wide range of colors, from pale to canary yellow, gold, honey, and brownish yellow. The lighter, brighter colors are the most common. Medium-sized or large stones are often seen, generally with a mixed oval cut having a rather large pavilion (to increase the depth of color). Because of their transparency, veillike or lacelike liquid inclusions and even foreign crystals are often visible inside. these stones. Like all corundum, they have considerable luster. Honey-colored stones, which are less common and often smaller, are equally lustrous and are given both oval and rectangular step cuts. The color can be quite similar to that of certain topazes.
Distinctive features Like all corundum, the yellow type can often be distinguished from other gems by its luster, but not from yellow chrysoberyl, which is very similar in this respect. The canary yellow color is not often found in other stones, except citrine, which is, however, a bit less lustrous. Yellow zircon has luster similar to that of yellow sapphire but is usually distinguishable through a lens by its much stronger birefringence, the facet edges appearing much more clearly duplicated and both facets and edges giving an impression of less hardness and greater brittleness. The inclusions in yellow sapphires are also fairly characteristic, at least when viewed through a lens. All in all, however, many yellow gems show some resemblance to yellow sapphire and must, therefore, be distinguished by their physical properties.
Occurrence Most light or canary yellow sapphire comes from Sri Lanka, and only a small proportion from Australia, which, however, supplies most of the less common honey, golden yellow or yellow-brown stones. Limited quantities are obtained from burma.
Value _ Somewhat surprisingly, even very attractive yellow sapphires with fine luster are of relatively low value compared with other secondary gems; they are, for example, worth a lot less than the'pink variety.
Simulants and synthetics Yellow sapphire was never really imitated by other substances until synthetic corundum was first produced. Since then canary and honey-yellow varieties have been widely manufactured. Like pink and colorless synthetic corundum, the yellow variety produced by the Verneuil flame fusion method is highly convincing and harder to distinguish from its natural counterparts than are rubies and sapphires produced in this way.