YUSH TECH

Ruby and Diamond
MoH (Hardness)
Diamond on scale 10
Ruby on scale 9 (Corundum)

Diamond and ruby are two of the hardest gemstones on Earth, with diamond having a hardness of 10 on the Mohs scale and ruby (corundum) having a hardness of 9. Their durability makes these gems ideal for ring stones.

Historically, diamond has symbolized strength and invincibility due to its hardness. In fact, the name "diamond" derives from the Greek word "adamas," meaning unconquerable and indestructible. Corundum, the mineral species for ruby and sapphire, is so durable that colorless corundum is used for watch crystals.

Seen here are a 100.20 carat colorless emerald cut diamond ring and a 25.59 carat Burmese ruby and diamond ring. Paired together, ruby and diamond make for a striking contrast of fire and ice!

Photo: Felix Wong/South China Morning Post via Getty Images

*Gems and gemstone*

Gem is a mineral or organic substance that is cut and polished and used as an ornament.

The qualities sought in gems are beauty, rarity, and durability. The unit of weight used for gems is the metric carat (200 mg).

Gems are usually cut to bring out their color and brilliance and to remove flaws.

Gems can be grouped into several categories using different criteria:

(a) The precious stones are diamond, some forms of corundum (e.g., ruby and sapphire) and emerald

(b) The chief semiprecious stones include amethyst, aquamarine, garnet, jade, moonstone, opal, quartz, topaz, tourmaline, and turquoise

(c) The organic gems are amber, coral, pearl, and jet

(d) The synthetic gems produced by using the chemical elements of natural stones and includes diamonds, emeralds, rubies, and sapphires

Popular gems The most popular and, therefore, the most important commercial gems include diamond, ruby, sapphire, emerald, and pearl.

The Diamond (at 10 on Mohs' scale, the hardest of all known substances) is a mineral and one of two crystalline forms of the element carbon.

It is the hardest substance known, and inferior stones are used as abrasives, in certain types of cutting tools, and as phonograph needles.

Gem diamonds were first found in stream beds in India and in Borneo; many are now extracted from volcanic pipes in South Africa,

Famous diamonds include the Koh-i-noor, now among the English Crown jewels; the Cullinan, from which 105 stones were cut; and the Blue Hope diamond.

Synthetic diamonds, produced since 1955, are now widely used industrially.

Though most highly prized when colourless, diamonds can be yellow, blue, pink, or other colours.

Corundum is an aluminum oxide mineral (Al2O3) occurring in both gem and in common varieties.

Ruby is coloured red by traces of chromium; the various colors of Sapphire, however, are produced by traces of iron and titanium in the corundum.

The ruby gem of the transparent red variety of corundum is found chiefly in Burma, Thailand, and Sri Lanka.

Star rubies (showing an internal star when cut with a rounded top) are rare. Synthetic rubies are produced by fusing pure aluminum oxide.

The sapphire gem is a transparent blue variety of corundum, found chiefly in Thailand, India, Sri Lanka, and Burma.

Like rubies, some sapphires show an internal star when cut with a round top.

Synthetic stones are made by fusing aluminum oxide, with titanium oxide added for color.

The transparent gems, chief of which are ruby and sapphire, are colourless, pink, red, blue (oriental aquamarine), green (oriental emerald), yellow, and violet.

Common varieties are used as abrasives (e.g., emery) and are blue-gray to brown in colour.

Corundum is found in North Carolina, Georgia, Montana, Republic of South Africa, and Tanzania.

The best gem corundum is found in Sri Lanka and elsewhere in Asia at places such as Mogok in Upper Burma, near Bangkok in Thailand, and Kashmir in India.

Beryl is an extremely hard beryllium and aluminum silicate mineral (Be3Al2Si6O18), occurring in crystals that may be of enormous size and are usually white, yellow, blue, green, or colourless.

Beryl gets its colour from traces of chromium and a little iron.

Beryl is the principal raw material for the element beryllium and its compounds.

It is commonly used as a gem, the most valued variety being the greenish emerald; the blue to bluish-green variety is aquamarine.

Aquamarine is a transparent blue to bluish-green variety of the mineral beryl and is used as a gem.

A typical jewellery store may carry several other kinds of gems: blue to bluish green aquamarine, pink to peach morganite, and other varieties (including those colored yellow green to green) of beryl; the complex borosilicate tourmaline, which may be pink to red (rubellite), blue (indicolite), bright green, or several other colors.

Tourmaline, complex aluminum and boron silicate mineral is also used as a gem.

Colors are red, pink, blue, green, yellow, violet, and black; sometimes it is colorless.

Two or more colors, arranged in zones or bands with sharp boundaries, may occur in the same stone.

Tourmalines are found in pegmatite veins in granites, gneisses, schists, and crystalline limestone.

The aluminosilicate topaz is straw- or golden-yellow, pink, green, blue, or brown in colour.

Topaz is an aluminum silicate mineral [Al2SiO4(F,OH)2], used as a gem.

Commonly colourless or some shade of yellow, the stone is transparent with a vitreous luster.

Topaz crystals occur in highly acidic igneous rocks and in metamorphic rocks.

Important sources include Brazil, Siberia, Burma, and Sri Lanka.

Gem varieties quartz (silicon dioxide) include amethyst (purple), chrysoprase (green), citrine (yellow to brown), rock crystal (colorless), and rose quartz; and Opal is a stone often with brilliant color flashes that is usually dark and white (Australia) or transparent (anywhere from colorless to orange-to-red and found in Mexico).

Opal, hydrous silica mineral (SiO2·nH2O) is formed at low temperatures from silica-bearing water, that can occur in cavities and fissures of any rock type.

Gem opal has rich iridescence and a remarkable play of colors, usually in red, green, and blue.

Most precious opals come from South Australia; other sources include Mexico (fire opal) and parts of the U.S.A as well as Sri Lanka.

The name garnet [Fe,Mg,Ca,Mn)3(Al,Fe,Cr)2(SiO4)3], is applied to a group of silicate minerals.

It is used chiefly as gems and abrasives.

The most common gem varieties are red, but garnets are also yellow, brown, and green. They are found in many types of rock throughout the world.

Less common gems include the beryllium aluminate chrysoberyl, especially its cat's-eye variety and the fascinating alexandrite variety, which appears green in daylight but appears red in artificial incandescent light; garnet, such as the red Bohemian pyropes and Indian almandines; peridot, a yellow green variety of the mineral species olivine, a magnesium-iron silicate; the magnesium-aluminate spinal, in its red and mauve varieties; tanzanite, a sapphire blue variety of the mineral species zoisite, a calcium-aluminum hydroxy silicate; and spodumene, in its green to yellow green varieties or the beautiful lavender lilac kunzite variety.

Turquoise in a hydrous aluminum and copper phosphate mineral Al2(OH)3PO4.H2O+Cu.

This usually found in microscopic crystals, it is opaque with a waxy luster, varying in color from greenish gray to (GEM-quality) sky blue.

Because of their porosity, the gem varieties absorb dirt and grease, changing the color to an unattractive green; exposure to heat or sunlight can also harm the color.

Classifications of Stones

A. Gems of the First Rank

Hardness, between 8 and 10.

Consisting of
pure carbon, or pure alumina, or with alumina predominating.

Fine specimens of very rare occurrence and of the highest value.

1. Diamond
2. Corundum (ruby, sapphire, etc.)
3. Chrysoberyl
4. Spinel

B. Gems of the Second Rank

Hardness, between 7 and 8 (except precious
opal).

Specific gravity usually over 3. Silica a prominent constituent.

In specimens of large
size and of fairly frequent occurrence.

Value
generally less than stones of Group A, but perfect specimens are more highly prized than
poorer specimens of

Group A.
5. Zircon
6. Beryl (emerald, etc.)
7. Topaz
8. Tourmaline
9. Garnet
10. Precious Opal

C. Gems of the Third Rank

These are intermediate in character, between
the true gems and the semi-precious stones.

Hardness between 6 and 7.

Specific gravity
usually greater than 2.5.

With the exception
of turquoise, silica is a prominent constituent
of all these stones.

Value usually not very
great; only fine specimens of a few members
of the group (cordierite, chrysolite, turquoise)
have any considerable value.

Specimens worth
cutting of comparatively rare occurrence, others
fairly frequent.

11. Cordierite
12. Idocrase
13. Chrysolite
14. Axinite
15. Kyanite
16. Staurolite
17. Andalusite
18. Chiastolite
19. Epidote
20. Turquoise

2. Semi-Prbcious Stones

These have some or all of the distinguishing
characters of precious stones, but to a less marked degree.

D. Gems of the Fourth Rank

Hardness, 4-7.
Specific gravity 2-3 (with the
exception of amber).

Colour and lustre are frequently prominent features.

Not as a rule
perfectly transparent: often translucent, or translucent at the edges only.

Wide distribution.
Value, as a rule, small.

21. Quartz
(a.) Rock-Crystal

A. Crystallised
a. quartz
b. Amethyst

c. Common Quartz
d. Prase
e. Aventurine
f. Cat's-Bye
g. Rose-Quartz

B. Chalcedony

a. Chalcedony
b. Agate (with onyx)
c. Carnelian
d. Plasma
e. Heliotrope
f. Jasper
g. Chrysoprase
C. Opal
a. Fire-Opal
b. Semi-Opal
c. Hydrophane
d. Cacholong
e. Jasper-Opal
f. Common-Opal

22. Feldspar

a. Adularia
b. Amazon-Stone

23. Labradorite
24. Obsidian
25. Lapis-lazuli
26. Haiiynite
27. Hypersthene
28. Diopside
29. Fluor-spar
30. Amber

E. Gems of the Fifth Rank

Hardness and specific gravity very variable.

Colour almost always dull.

Never transparent.
Low degree of lustre.

Value very insignificant,
and usually dependent upon the work bestowed
upon them.

These stones, as well as many of
the preceding group, are not faceted, but worked by the ordinary lapidary in the large stone-cutting works.

31. Jet
32. Nephrite
33. Serpentine
34. Agalmatolite
35. Steatite
36. Pot-stone
37. Diallage
38. Bronzite
39. Bastite
40. Satin-spar (calcite)
41. Marble
42. Satin-spar
43. Alabaster
44. Malachite
45. Iron Pyrites
46. Bhodochrogite
47. Hematite and aragonite)
48. Prehnite
49. Elajolite
(gypsum)
50. Natrolite
51. Lava
52. Quartz-breccia
53. Lepidolite

'Among the stones enumerated above are some that are never worked as personal ornaments, and many of them have probably never been heard of by American jewellers.

Because of the pre-eminence of Dr. Max
Bauer's Precious Stones, in the realm which that great work so effectually covers, the arrangement of precious stones made by the distinguished author, and followed throughout in his work, is of interest.

It is as follows:

Diamond
Corundum
Ruby, Sapphire, including star-sapphire and white sapphire, " Oriental aquamarine,"
" Oriental emerald," " Oriental chrysolite," " Oriental topaz," " Oriental hyacinth,"
" Oriental amethyst," adamantine-spar.

*Spinel*
" Euby-spinel," " Balas-ruby," « Alamandine spinel," Eubicelle, Blue-spinel, Ceylonite.

Chrysoberyl

Cymophane ("Oriental cat's-eye"), Alexandrite.

Beryl

Emerald, Aquamarine, " Aquamarine-chrysolite," Golden beryl.

Euclase
Phenakite
Topaz
Zircon
Hyacinth

Garnet Group

Hessonite (Cinnamon stone), Spessartite, Almandine, Pyrope (Bohemian garnet, "Cape ruby," and Rhodolite), Demantoid, Grossularite, Melanite, Topazolite.

Tourmaline

Opal

Precious opal.

Fire-opal, Common opal.
Turquoise
Bone-turquoise
Lazulite
Callainite
Olivine
Chrysolite, Peridot.

Cordierite
Idocrase
Axinite
Kyanite
Staurolite
Andalusite
Chiastolite.

Epidote
Piedmontite
Dioptase.