In mineralogy, diamond is the allotrope of carbon where the carbon atoms are arranged in an isometric-hexoctahedral crystal lattice. Its hardness and high dispersion of light make it useful for industrial applications and jewelry. It is the hardest known naturally-occurring mineral. It is possible to treat regular diamonds under a combination of high pressure and high temperature to produce diamonds (known as Type-II diamonds) that are harder than the diamonds used in hardness gauges. Presently, only aggregated diamond nanorods, a material created using ultrahard fullerite (C60) is confirmed to be harder, although other substances such as cubic boron nitride, rhenium diboride and ultrahard fullerite itself are comparable.

Diamonds are specifically renowned as a material with superlative physical qualities; they make excellent abrasives because they can be scratched only by other diamonds, borazon, ultrahard fullerite, rhenium diboride, or aggregated diamond nanorods, which also means they hold a polish extremely well and retain their lustre. Approximately 130 million carats () are mined annually, with a total value of nearly USD $9 billion, and about are synthesized annually.

The name diamond derives from the ancient Greek ?????? (adamas) "invincible", "untamed", from ?- (a-), "un-" + ????? (damá?), "to overpower, to tame". They have been treasured as gemstones since their use as religious icons in ancient India and usage in engraving tools also dates to early human history. Popularity of diamonds has risen since the 19th century because of increased supply, improved cutting and polishing techniques, growth in the world economy, and innovative and successful advertising campaigns. They are commonly judged by the ?four Cs?: carat, clarity, color, and cut.

Roughly 49% of diamonds originate from central and southern Africa, although significant sources of the mineral have been discovered in Canada, India, Russia, Brazil, and Australia. They are mined from kimberlite and lamproite volcanic pipes, which can bring diamond crystals, originating from deep within the Earth where high pressures and temperatures enable them to form, to the surface. The mining and distribution of natural diamonds are subjects of frequent controversy such as with concerns over the sale of conflict diamonds (aka blood diamonds) by African paramilitary groups.

Gold () is a chemical element with the symbol Au (from its Latin name aurum) and atomic number 79. It is a highly sought-after precious metal which has been used as money, a store of value and in jewelery since the beginning of recorded history. The metal occurs as nuggets or grains in rocks, underground "veins" and in alluvial deposits. It is one of the coinage metals. Gold is dense, soft, shiny and the most malleable and ductile substance known. Pure gold has a bright yellow color traditionally considered attractive.

Gold formed the basis for the gold standard used before the collapse of the Bretton Woods system. The ISO currency code of gold bullion is XAU.

Modern industrial uses include dentistry and electronics, where gold has traditionally found use because of its good resistance to oxidative corrosion.

Chemically, gold is a transition metal and can form trivalent and univalent cations upon solvation. , but is attacked by chlorine, fluorine, aqua regia and cyanide. Gold dissolves in mercury, forming amalgam alloys, but does not react with it. Gold is insoluble in nitric acid, which will dissolve silver and base metals, and this is the basis of the gold refining technique known as "inquartation and parting". Nitric acid has long been used to confirm the presence of gold in items, and this is the origin of the colloquial term "acid test," referring to a gold standard test for genuine value.

Silver () is a chemical element with the symbol "Ag" (, from the Ancient Greek: ???????? - arg?ntos, gen. of ??????? - arg?eis, "white, shining" ) and atomic number 47. A soft, white, lustrous transition metal, it has the highest electrical conductivity of any element and the highest thermal conductivity of any metal. It occurs as a pure free metal (native silver) and alloyed with gold (electrum), as well as in various minerals, such as argentite and chlorargyrite. Most silver is produced as a by-product of copper, gold, lead, and zinc mining.

Silver has been known since ancient times and has long been valued as a precious metal, used to make ornaments, jewellery, high-value tableware and utensils (hence the term "silverware") and currency coins. Today, silver metal is used in electrical contacts and conductors, in mirrors and in catalysis of chemical reactions. Its compounds are used in photographic film and dilute solutions of silver nitrate and other silver compounds are used as disinfectants. Although the antimicrobial uses of silver have largely been supplanted by the use of antibiotics, further research into its clinical potential is in progress.

Platinum () is a chemical element with the atomic symbol Pt and an atomic number of 78. It is in group 10 of the Periodic Table of Elements. A heavy, malleable, ductile, precious, gray-white transition metal, platinum is resistant to corrosion and occurs in some nickel and copper ores along with some native deposits. Platinum is used in jewelry, laboratory equipment, electrical contacts, dentistry, and automobile emissions control devices. Platinum bullion has the ISO currency code of XPT. As of October 2nd, 2008, Platinum was worth $1,038.00 per troy ounce (approximately $33 per gram).

Zircon is a mineral belonging to the group of nesosilicates. Its chemical name is zirconium silicate and its corresponding chemical formula is ZrSiO4. Hafnium is almost always present in quantities ranging from 1 to 4%. The crystal structure of zircon is tetragonal crystal system. The natural color of zircon varies between colorless, yellow-golden, red, brown, and green. Colorless specimens that show gem quality are a popular substitute for diamond; these specimens are also known as "Matura diamond". It is not to be confused with cubic zirconia, a synthetic substance with a completely different chemical composition.

The name either derives from the Arabic word zarqun, meaning vermilion, or from the Persian zargun, meaning golden-colored. These words are corrupted into "jargoon", a term applied to light-colored zircons. Yellow zircon is called hyacinth, from a word of East Indian origin; in the Middle Ages all yellow stones of East Indian origin were called hyacinth, but today this term is restricted to the yellow zircons.

Zircon is regarded as the traditional birthstone for December.

Titanium () is a chemical element with the symbol Ti and atomic number 22. It is a light, strong, lustrous, corrosion-resistant (including to sea water and chlorine) transition metal with a grayish color. Titanium can be alloyed with iron, aluminium, vanadium, molybdenum, among other elements, to produce strong lightweight alloys for aerospace (jet engines, missiles, and spacecraft), military, industrial process (chemicals and petro-chemicals, desalination plants, pulp, and paper), automotive, agri-food, medical prostheses, orthopaedic implants, dental endodontic instruments and files, dental implants, sporting goods, jewelry, mobile phones, and other applications.

Titanium was discovered in England by William Gregor in 1791 and named by Martin Heinrich Klaproth for the Titans of Greek mythology.

The element occurs within a number of mineral deposits, principally rutile and ilmenite, which are widely distributed in the Earth's crust and lithosphere, and it is found in almost all living things, rocks, water bodies, and soils. The metal is extracted from its principal mineral ores via the Kroll process or the Hunter process. Its most common compound, titanium dioxide, is used in the manufacture of white pigments. Other compounds include titanium tetrachloride (TiCl4) (used in smoke screens/skywriting and as a catalyst) and titanium trichloride (TiCl3) (used as a catalyst in the production of polypropylene).

The two most useful properties of the metal form are corrosion resistance, and the highest strength-to-weight ratio of any metal. In its unalloyed condition, titanium is as strong as some steels, but 45% lighter. There are two allotropic forms and five naturally occurring isotopes of this element; 46Ti through 50Ti, with 48Ti being the most abundant (73.8%). Titanium's properties are chemically and physically similar to zirconium.