There are a lot of varieties of quartz on the market but there are also varieties of so-called quartz that are not actually quartz or are altered quartz. Your seller SHOULD be up front and tell you what you’re buying.
Typical quartz varieties include:
quartz (clear, colorless)
milky quartz (translucent white)
rose quartz (pink/milky pink)
amethyst (purple quartz)
citrine (yellow/yellow green/yellow brown quartz – often heat treated to get golden/orange colors; natural is dichroic)
Carats have been the standard for weighing gems since ancient times. “The name is derived from the see kuara of the African Coraltree or from the kernel (Greek keratiton) of the Carob bean.”  One carat is a unit of mass equivalent to 200 micrograms, 0.2 grams, 0.007 ounces, or about the same as a standard paper clip.
Both cut and stone density affect the total carat weight of a stone. For example, I sampled five 5mm round sapphires and the carat weight varied from 0.615cts to 0.835cts as a result of differences in how each stone was cut. To compare to other gemstones, I found a 5mm round andalusite weighing in at 0.45cts, kyanite at 0.6cts, and a brilliant cut diamond at 0.5cts.
One thing to note as you are looking at gemstones is that larger stones are more rare and will likely cost more per carat than the more easily obtainable, small stones.
 Gemstones of the World: Newly Revised & Expanded Fourth Edition by Walter Schumann, p30
Although I am normally not a fan of yellow stones, citrine has become one of my favorite crystals.
Citrine is a type of quartz that can be found in shades of yellow to reddish brown, with iron as the primary colorant. Like all quartz, citrine has a Mohs hardness of 7, so it is moderately hard but can scratch and get chipped.
Citrine is sensitive both to heat and sunlight – both could affect the color of the stone. Try to keep your citrine jewelry or stones away from prolonged exposure to intense heat or light and store in a cool, dark place when not in use. Clean your citrine jewelry with water mixed with a small amount of mild liquid hand soap with a soft cloth, rinse with water and dry with a soft cloth.
Many commercial citrines have been heat treated (often from amethyst or smoky quartz). “Almost all heat-treated citrines have a reddish tint. The natural citrines are mostly pale yellow.” Some natural citrines can also have a reddish tint and heat-treated citrines can be a pale lemon yellow.
Citrine has a number of metaphysical associations with it, including:
dissipates negative energies
attracts wealth, success prosperity & abundance
enhances body’s healing energy
opens mind to intuition
helps adapt to change
Chakra: solar plexus
 Gemstones of the World: Newly Revised & Expanded Fourth Edition by Walter Schumann, p.136
At a recent show, we were asked about which stone is considered the “angel stone”. Apparently, there are multiple stones which are considered to be helpful for communicating with, contacting, or working with angels. Below are some of the stones I found, along with a very brief description of the angelic attribution for each.
Amethyst: said to have soothing energy that helps connect with angels.
Angelite: the white markings on these blue stones are reminiscent of angel wings; attributes of this stone include bringing awareness to the angelic realms and aiding communication with angels.
Blue lace agate: considered to be helpful for communicating with angels.
Celestite: supposed to provide access to the angelic realms.
Golden danburitie: believed to help one embody angelic wisdom.
Petalite: sometimes called the “stone of the angels” because it is believed to encourage one to demonstrate angelic behavior.
Seraphinite: characterized by feathery marks which may resemble angel wings; said to be helpful facilitating celestial contact.
Angel aura quartz, which is created by finely powdered platinum, silver, and other minerals are bonded to quartz, is also considered to be an angelic stone because the rainbow colors created by the coating seem like angel wings to some.
With the recent excitement over asteroids and the meteor impact in Russia, it reminded me that some of the gemstones and minerals we enjoy on Earth have their origins in outer space.
While tektite forms from Earth material, it is believed that tektites are formed only as a result of extraterrestrial impacts. Tektite resembles volcanic glass but has a significantly lower water content. These bumpy rocks often appear in a drop shape although some people have faceted tektite like a gemstone. Moldavite is a name given to a greenish form of tektite.
According to an article from the National Science Foundation, natural black diamonds formed in outer space. “The presence of hydrogen in the carbonado diamonds indicates an origin in a hydrogen-rich interstellar space.” This also seems to provide an explanation as to why black diamonds are not found in mines and why it is so unusual to find good quality natural black diamonds over 1 carat in size (think fragments of objects hitting the Earth). Note that many black diamonds in jewelry stores will have fine print to indicate that the stones were irradiated or radiation treated (for color) – those stones are most likely not the same chemical composition as natural black diamonds.
Peridot, also called olivine, has not only been found in meteorites but it has also been found on Mars. This green gemstone is also formed deep inside the Earth and can be expelled during volcanic eruptions. I will never look at peridot the same!
While most people know to keep lead from their children, many people don’t think twice about their natural gemstone jewelry (or even tumbled rocks). At first, I was thinking primarily about cinnabar – which has a high mercury content and is frequently carved into ornate designs. With some research, I found that there are a significant number of other stones which contain substances that should not be ingested (or in some cases, the dust is problematic).
Below is an alphabetical list of gemstones/minerals I found which contain toxins:
Adamite – zinc, copper
Amazonite – copper
Amber – toxic dust, fumes
Angelite – lead, sulfur
Aragonite – pollutants
Atacamite – copper
Auricalcite – zinc and copper
Auripignment – arsenic
Azurite – copper
Boji-Stones – may contain sulfur
Bronchantite – copper
Cerrusite – sulfur, molybdenum
Chalcantite – copper
Chalcopyrite (Peacock Stone, Peacock Ore) – copper and sulfur
Chrysocolla – copper
Cinnabar – mercury
Cobaltocalcite (Pink Cobalt Calcite) – cobalt
Conicalcite – copper
Copper – copper
Coral – bacteria and pollutants
Cuprite – copper
Diopside – copper
Dioptase – copper
Eliat Stone – copper
Emerald – aluminum
Garnet – aluminum
Gem Silica – copper
Galena/ Galenite – lead
Garnierite (Genthite, Falcondoite) – nickel
Hiddenite – aluminum
Iolite – aluminum
Kansas Pop Rocks – may contain sulfur
Kunzite – aluminum
Kyanite – aluminum
Labradorite – aluminum
Lapis Lazuli – copper, sulfur
Magnetite (Lodestone) – iron in large quantities
Malachite – copper suphate
Marcasite (Markasite) – sulfur
Meteorite – may contain many toxic substances
Mohawkite – copper, arsenic
Moldavite – aluminum
Molybdenum – molybdenum
Moonstone – aluminum
Mother of Pearl – bacteria and pollutants
Opal – toxic dust
Pearl – bacteria and pollutants
Psiomelane – barium
Pyrite (Fool’s Gold, Inca Gold) – sulfur
Quartz (all types) – toxic dust
Realgar – sulfur and arsenic
Rhodocrosite – lead
Ruby – aluminum
Sapphire – aluminum
Serpentine – asbestos, may contain nickel
Sodalite – aluminum
Spinel – may contain aluminum, zinc
Stibnite – lead, antimony
Smithsonite (Galmei, Zinc spar)- zinc, may contain copper