Peridot is silicate of magnum and iron. Today many thing that peridot is variety of chrysolith, it should be mentioned that in past only transparent stones were considered as chrysolith. We rarely see dark yellow, golden peridots though they exist in nature. The word itself comes from french, though its true etymology is unknown.
Amethyst is a violet variety of quartz often used in jewelry.it has purple color which can vary to violet or dark pink. If heated to 200 degree it loses its color and retrieves it after cooling. Name of stone comes from nymph in old myth. According to it name of nymph was ametis and she had power to protect human from powers of Dionysus. she was under protection of Artemis who turned nymph in stone, and gave it powers to withstand drinking (ametistoz - meaning sober). it is not excluded that name of stone is due to its color, which is dark wine-ish.
Topaz is a silicate mineral of aluminium and fluorine. Pure topaz is colorless and transparent but is usually tinted by impurities; typical topaz is wine, yellow, pale gray, reddish-orange, or blue brown. It can also be made white, pale green, blue, gold, pink , reddish-yellow or opaque to transparent/translucent. The name of stone comes form island where these stones were excavated first. Name of the Island was topazos, no st. Johns Island. Another versions suggests that name comes from old sanskrit language where "tapas" means fire, heat, we cant exclude this version too.
Citrine is a variety of quartz whose color ranges from a pale yellow to brown. Natural citrines are rare. Word citrine was first used in 1747 year. Its origins come from word "citerus" which means lemon, considering color of stone this version is very believable. Also we should mention that if we heat quartz it becomes like citrine like.
Aquamarine is a blue or turquoise variety of beryl. It occurs at most localities which yield ordinary beryl.Clear yellow beryl, such as that occurring in Brazil, is sometimes called aquamarine chrysolite. Word itself was used for first time in XVII century by Boeci de bot.
According to horoscope each month has its own zodiac sign. Same accordance to horoscope also says that each horoscope signs has its mark on person who was born in its period. On the other hand each sign has its own stone. Wearing stone which is in accordance with your zodiac sign has an positive effect on person in many ways. On list below you can see sings connected to its stones: Aquarius - Amber, amethyst, purple. Pisces - Opal, corral, agate, aquamarine. Aries - Agate, aquamarine, citrin,diamond, emerald. Taurus - Diamond, tourmaline, quartz. Gemini - Aquamarine, sapphire, emerald, pearl. Cancer - Citrin, ruby, opal, pearl. Leo - Citrin, amber, purple, Diamond, onyx, opal, peridot, ruby. Virgo - Quartz, peridot, amethyst, agate, purple, opal. Libra - Quartz, tourmaline, citrin, opal. Scorpio - Opal, peridot, ruby. Sagittarius - Topaz, purple, quartz.