Ruby in the context of Chromium

Corundum is a crystalline form of aluminium oxide (Al₂O₃) typically containing traces of iron, titanium, vanadium, and chromium. It is a rock-forming mineral. It is a naturally transparent material, but can have different colors depending on the presence of transition metal impurities in its crystalline structure. Corundum has two primary gem varieties: ruby and sapphire. Rubies are red due to the presence of chromium, and sapphires exhibit a range of colors depending on what transition metal is present. A rare type of sapphire, padparadscha sapphire, is pink-orange.

The name "corundum" is derived from the Tamil-Dravidian word kurundam (ruby-sapphire) (appearing in Sanskrit as kuruvinda).

A ring is a round band, usually made of metal, worn as ornamental jewelry. The term "ring" by itself denotes jewellery worn on the finger; when worn as an ornament elsewhere, the body part is specified within the term, e.g., earrings, neck rings, arm rings, and toe rings. Rings fit snugly around or in the part of the body they ornament, so bands worn loosely, like a bracelet, are not rings. Rings may be made of almost any hard material: wood, bone, stone, metal, glass, jade, gemstone or plastic. They may be set with gemstones (diamond, ruby, sapphire or emerald) or with other types of stone or glass.

Although some people wear rings as mere ornaments or as conspicuous displays of wealth, rings have symbolic functions respecting marriage, exceptional achievement, high status or authority, membership in an organization, and the like. Rings can be made to sport insignia which may be impressed on a wax seal or outfitted with a small compartment in which to conceal things.

A necklace is an article of jewellery that is worn around the neck. Necklaces may have been one of the earliest types of adornment worn by humans. They often serve ceremonial, religious, magical, or funerary purposes and are also used as symbols of wealth and status, given that they are commonly made of precious metals and stones.

The main component of a necklace is the band, chain, or cord that wraps around the neck. These are most often rendered in precious metals such as gold, silver, and platinum. Necklaces often have additional attachments suspended or inset into the necklace itself. These attachments typically include pendants, lockets, amulets, crosses, and precious and semiprecious materials such as diamond, pearls, rubies, emeralds, garnets, and sapphires. They are made with many different type of materials and are used for many things and sometimes classified as clothing.

A gemstone (also called a fine gem, jewel, precious stone, semiprecious stone, or simply gem) is a piece of mineral crystal which, when cut or polished, is used to make jewelry or other adornments. Certain rocks (such as lapis lazuli, opal, and obsidian) and occasionally organic materials that are not minerals (such as amber, jet, and pearl) may also be used for jewelry and are therefore often considered to be gemstones as well. Most gemstones are hard, but some softer minerals such as brazilianite may be used in jewelry because of their color or luster or other physical properties that have aesthetic value. However, generally speaking, soft minerals are not typically used as gemstones by virtue of their brittleness and lack of durability.

Found all over the world, the industry of coloured gemstones (i.e. anything other than diamonds) is currently estimated at US$1.55 billion as of 2023 and is projected to steadily increase to a value of $4.46 billion by 2033.

Sapphire is a precious gemstone, a variety of the mineral corundum, consisting of aluminium oxide (α-Al₂O₃) with trace amounts of elements such as iron, titanium, cobalt, lead, chromium, vanadium, magnesium, boron, and silicon. The name sapphire is derived from the Latin word sapphirus, itself from the Greek word sappheiros (σάπφειρος), which referred to lapis lazuli. It is typically blue, but natural "fancy" sapphires also occur in yellow, purple, orange, and green colors; "parti sapphires" show two or more colors. Red corundum stones also occur, but are called rubies rather than sapphires. Pink-colored corundum may be classified either as ruby or sapphire depending on the locale. Commonly, natural sapphires are cut and polished into gemstones and worn in jewelry. They also may be created synthetically in laboratories for industrial or decorative purposes in large crystal boules. Because of the remarkable hardness of sapphires – 9 on the Mohs scale (the third-hardest mineral, after diamond at 10 and moissanite at 9.5) – sapphires are also used in some non-ornamental applications, such as infrared optical components, high-durability windows, wristwatch crystals and movement bearings, and very thin electronic wafers, which are used as the insulating substrates of special-purpose solid-state electronics such as integrated circuits and GaN-based blue LEDs. It occurs in association with ruby, zircon, biotite, muscovite, calcite, dravite and quartz.

Aluminium oxide (or aluminium(III) oxide) is a chemical compound of aluminium and oxygen with the chemical formula Al₂O₃. It is the most commonly occurring of several aluminium oxides, and specifically identified as aluminium oxide. It is commonly called alumina and may also be called aloxide, aloxite, ALOX or alundum in various forms and applications and alumina is refined from bauxite. It occurs naturally in its crystalline polymorphic phase α-Al₂O₃ as the mineral corundum, varieties of which form the precious gemstones ruby and sapphire, which have an alumina content approaching 100%. Al₂O₃ is used as feedstock to produce aluminium metal, as an abrasive owing to its hardness, and as a refractory material owing to its high melting point.

The papal tiara is a crown that was worn by popes of the Catholic Church from as early as the 8th century to the mid–20th century. It was last used by Pope Paul VI in 1963, and only at the beginning of his reign.

The name tiara refers to the entire headpiece, including the various crowns, circlets, and diadems that have adorned it through the ages, while the three-tiered form that it took in the 14th century is also called the triregnum or the triple crown, and sometimes as the triple tiara.

A collectable, collectible, or collector's item is any object regarded as being of value or interest to a collector. Collectable items are not necessarily monetarily valuable or uncommon. There are numerous types of collectables and terms to denote those types. An antique is a collectable that is old. A curio is something deemed unique, uncommon, or weird, such as a decorative item. A manufactured collectable is an item made specifically for people to collect.

Aluminium oxides or aluminum oxides are a group of inorganic compounds with formulas including aluminium (Al) and oxygen (O).

• Aluminium(I) oxide (Al₂O)
• Aluminium(II) oxide (AlO) (aluminium monoxide)
• Aluminium(III) oxide (aluminium oxide), (Al₂O₃), the most common form of aluminium oxide, occurring on the surface of aluminium and also in crystalline form as corundum, sapphire, and ruby.

Cardinal gems are gemstones which have traditionally been considered precious above all others. The classification of the cardinal gems dates back to antiquity, and was largely determined by ceremonial or religious use as well as rarity. The term has largely fallen out of use.

Mining in Afghanistan is controlled by the Ministry of Mines and Petroleum in Kabul, which has offices in different parts of the country. Afghanistan has over 1,400 mineral fields, containing barite, chromite, coal, copper, gold, iron ore, lead, natural gas, petroleum, precious and semi-precious stones, salt, sulfur, lithium, talc, and zinc, among many other minerals. Gemstones include high-quality emeralds, lapis lazuli, red garnet and ruby. According to a joint study by The Pentagon and the United States Geological Survey, Afghanistan has an estimated US$1 trillion of untapped minerals.

There are six lapis mines in Afghanistan, the largest being located in Badakhshan province. There are around 12 copper mines in the country, including the Aynak copper deposit located in Logar province. Afghanistan's significance from an energy standpoint stems from its geographical position as a transit route for oil, natural gas, and electricity exports from Central Asia to South Asia and the Arabian Sea. This potential includes the construction of the Trans-Afghanistan Pipeline gas pipeline. The first Afghan oil production began in late 2012.

Underground hard-rock mining refers to various underground mining techniques used to excavate "hard" minerals, usually those containing metals, such as ore containing gold, silver, iron, copper, zinc, nickel, tin, and lead. It also involves the same techniques used to excavate ores of gems, such as diamonds and rubies. Soft-rock mining refers to the excavation of softer minerals, such as salt, coal, and oil sands.