What gems can have asterism?
Common examples of gems with asterism are ruby and sapphire with six-pointed stars caused by tiny exsolution rutile needles, or black diopside with four-pointed stars produced by exsolution inclusions of black magnetite. Rose quartz, garnets, moonstone and other gems can also have asterism effect.
What is asterism in a sapphire?
What is asterism? Asterism is the star effect seen by reflection and scattering of light in cabochon-cut stones with suitably oriented rod-like inclusions or platelets.
What is the difference between Chatoyancy and asterism?
The name Chatoyancy coming from the French to mean a cat’s eye is when a parallel ray, that bares resemblance to the slit in a cat’s eye, is seen on the surface of the stone. When the stone shows four or more ray this is known as asterism or a star.
What is a Starstone?
: an asteriated stone especially : star sapphire.
What is an example of asterism?
The Summer Triangle is an example of an asterism: a group of stars that form a recognizable pattern or shape. The Big Dipper, the Little Dipper and the Great Square of Pegasus are other examples of asterisms.
How do you write asterism?
In typography, an asterism, ⁂, is a typographic symbol consisting of three asterisks placed in a triangle, which is used for a variety of purposes. The name originates from the astronomical term for a group of stars….
- & ampersand.
- @ at sign.
- ^ caret.
- / slash.
- \ backslash.
- … ellipsis.
- * asterisk.
- ⁂ asterism.
Is Moonstone a Chatoyant?
Moonstone bodycolors vary widely. They can be green, yellow to brown, or gray to nearly black. Along with adularescence, some moonstones show chatoyancy, also called the cat’s-eye effect.
What is the difference between labradorite and Spectrolite?
Spectrolite is a form of labradorite only found in Finland. Both labradorites and spectrolites have dark base colors, but labradorite’s base is more transparent and spectrolite’s is more opaque. Other than that, origin is the primary differentiation between the two.
What is mineral asterism?
asterism, in mineralogy, starlike figure exhibited in light reflected or transmitted by some crystals.
What causes asterism in gems?
The star-effect or “asterism” is caused by the difference in refractive index between the host material and that of the dense inclusions of tiny fibers of rutile (also known as “silk”). The stars are caused by the light reflecting from needle-like inclusions of rutile aligned perpendicularly to the rays of the star.
What is an asterism name 2 examples?
These are called asterisms. Some well-known asterisms include: The Big Dipper and the Little Dipper – The Big Dipper is also known as the Plow (or Plough, in the United Kingdom). Its stars are part of the constellation Ursa Major, the Great Bear.
What are asterisms used for?
The constellations are, technically, regions the sky is divided into in order to help with identifying where objects are located on the sky. In addition to the star patterns within the constellations, there are a variety of other familiar patterns of stars. These are called asterisms.
What is the meaning of the term asterism?
Asterism (from Ancient Greek: ἀστήρ star), the property of a star stone (asteria), is the phenomenon of gemstones exhibiting a star-like concentration of reflected or refracted light when cut en cabochon (shaped and polished rather than faceted).
What kind of gemstone has an asterism?
An asterism is an optical phenomenon displayed by some rubies, sapphires, and other gems (e.g. garnet, diopside, spinel) of an enhanced reflective area in the shape of a “star” on the surface of a cabochon cut from the stone. Star sapphires and rubies display the property from titanium dioxide impurities ( rutile) present in them.
What does it mean when a sapphire has an asterism?
An asterism is an optical phenomenon displayed by some rubies, sapphires, and other gems (e.g. garnet, diopside, spinel) of an enhanced reflective area in the shape of a “star” on the surface of a cabochon cut from the stone.
What is the meaning of the three asterisks?
2. a property of some crystallized minerals of showing a starlike luminous figure in transmitted light or, in a cabochon-cut stone, by reflected light. 3. three asterisks (⁂ or ⁂) printed before a passage to draw attention to it. asterism. Rare. a constellation or small group of unrelated stars.