Amethyst is a purple variety of quartz (SiO₂), colored by trace iron and natural irradiation. It is found in geodes and igneous rocks in countries like Brazil, Uruguay, Russia, Zambia, South Korea, and the USA. Its color ranges from light lavender to deep purple.

Aquamarine is a blue to blue-green gemstone found mainly in countries such as Brazil, Madagascar, Nigeria, Pakistan, Afghanistan, and the United States. Its color comes from iron impurities within the crystal. Aquamarine has a Mohs hardness of 7.5–8, making it durable enough for everyday jewelry. Chemically, it is beryllium aluminum silicate with the formula Be₃Al₂Si₆O₁₈, and it is the blue variety of the mineral beryl.

Citrine is most commonly found in Brazil, with additional sources in Madagascar, Bolivia, Spain, Russia, and the United States. It ranges in color from pale yellow to golden yellow and orange-brown, caused by trace amounts of iron. Citrine has a Mohs hardness of 7, making it suitable for everyday wear. Chemically, it is silicon dioxide (quartz) with the formula SiO₂.

Diopside is found in igneous and metamorphic rocks, with notable sources in Russia, Italy, Pakistan, South Africa, Myanmar, Madagascar, and the United States. It is typically green, but can also appear light to dark green, bluish-green, brown, or black, depending on trace elements. Diopside has a Mohs hardness of 5.5–6.5, making it softer than many common gemstones. Chemically, it is a calcium magnesium silicate with the formula CaMgSi₂O₆.

Garnet is found worldwide in metamorphic and igneous rocks, with major sources including India, Sri Lanka, Madagascar, Brazil, Russia, Tanzania, South Africa, and the United States. Garnet occurs in a wide range of colors, most commonly red, but also green, orange, yellow, purple, brown, and nearly black, depending on the specific variety. Garnet has a Mohs hardness of about 6.5–7.5. Chemically, garnet is a group of silicate minerals with the general formula X₃Y₂(SiO₄)₃, where X and Y represent different metal elements such as iron, magnesium, calcium, aluminum, or chromium.

Moonstone is found primarily in Sri Lanka, with additional sources in India, Madagascar, Myanmar, Australia, and the United States. It is typically colorless to white, but can also appear peach, gray, yellow, green, or blue, often showing a soft, glowing effect called adularescence. Moonstone has a Mohs hardness of 6–6.5, making it moderately soft and better suited for protected jewelry settings. Chemically, moonstone is a variety of feldspar, specifically potassium aluminum silicate, with the formula KAlSi₃O₈.

Opal is found most famously in Australia, which produces the majority of the world’s precious opal, with additional sources in Ethiopia, Mexico, Brazil, Honduras, and the United States. Opal can be white, black, gray, blue, green, yellow, orange, or red, and many varieties display a shifting rainbow effect known as play-of-color. Opal has a Mohs hardness of 5.5–6.5, making it relatively soft and more delicate than many gemstones. Chemically, opal is hydrated silicon dioxide, with the formula SiO₂·nH₂O.

Peridot is found in volcanic and mantle-derived rocks, with major sources including Myanmar, Pakistan, China, Vietnam, the United States (Arizona), Sri Lanka, and Tanzania. It is characteristically olive green to yellow-green, with the color caused by iron within the crystal structure. Peridot has a Mohs hardness of 6.5–7, making it fairly durable but still softer than gems like sapphire or topaz. Chemically, peridot is the gem variety of olivine, a magnesium iron silicate with the formula (Mg,Fe)₂SiO₄.

Ruby (cabochon cut) is found primarily in Myanmar (Burma), with additional sources in Thailand, Sri Lanka, Mozambique, Madagascar, Tanzania, and Afghanistan. It is typically deep red to purplish red, with the color caused by chromium; cabochon-cut rubies often show visible inclusions and may display effects like asterism (star rubies). Ruby has a Mohs hardness of 9, making it one of the hardest gemstones. Chemically, ruby is a variety of corundum (aluminum oxide) with the formula Al₂O₃.

Sapphire is found primarily in Sri Lanka, Myanmar, Madagascar, Thailand, Australia, and Montana (USA). It is most commonly blue, but can also occur in pink, yellow, green, purple, and colorless varieties; trace elements like iron, titanium, and chromium give it its color. Sapphire has a Mohs hardness of 9, making it extremely durable. Chemically, sapphire is a variety of corundum (aluminum oxide) with the formula Al₂O₃.

Spinel is found in Myanmar, Sri Lanka, Vietnam, Tanzania, Afghanistan, and Madagascar. It occurs in a wide range of colors, most commonly red, but also pink, blue, purple, brown, black, and colorless. Spinel has a Mohs hardness of 7.5–8, making it fairly durable for jewelry. Chemically, spinel is a magnesium aluminum oxide with the formula MgAl₂O₄.

Green topaz is found primarily in Brazil, with additional sources in Pakistan, Russia, Sri Lanka, Nigeria, Mexico, and the United States. It ranges in color from pale mint green to deeper bluish-green, though most green topaz on the market is irradiated and heat-treated to achieve or enhance the color. Green topaz has a Mohs hardness of 8, making it a durable gemstone suitable for everyday jewelry. Chemically, topaz is an aluminum silicate with fluorine and hydroxyl, with the formula Al₂SiO₄(F,OH)₂.

Tourmaline is found in Brazil, Madagascar, Afghanistan, Pakistan, Nigeria, Mozambique, and the United States (California and Maine). It occurs in a wide range of colors, including pink, red, green, blue, yellow, brown, black, and multicolored varieties; color depends on trace elements like iron, manganese, and lithium. Tourmaline has a Mohs hardness of 7–7.5, making it reasonably durable for jewelry. Chemically, tourmaline is a complex boron silicate, generally represented by the formula (XY₃Z₆)(Si₆O₁₈)(BO₃)₃(OH,F)₄, where X, Y, and Z are various metal ions.