When considering the energetic aspects of gemstones, it is more important to first consider the aspects of one’s personality or total “state of being”, and then look at the gemstone properties that most relate.
More than just basing one’s choice on birthday or favorite colors, the idea is to find the gemstone that is most appropriate and that would be of most benefit to the total “vibratory pattern” of the person. They can help strengthen and guide the individual along the right path, by enhancing more than changing things with energetic influences.
Certain stones can influence specific physical or mental conditions.
For example, http://otakuyume.angelfire.com mentions these stone properties as they relate to :
General protection—beryl, lapis ligurius
Protection from colds—carbon steel
Prevention of personal anger—opal, pearl, amethyst
Influencing the mental choice-bloodstone, sard onyx
Strengthening abilities during exertion—agate, amethyst
Strengthening the body—lapis lazuli, bloodstone, moonstone, pearl, topaz
Gaining self-assurance—lapis lazuli
I’d like to talk about the properties of yellow topaz.
It is the birthstone of November, and it is the yellow color of the Third Chakra, one of the seven energy centers of the body, located at the solar plexus. It is the center of emotions. The planet of influence is Jupiter.
The ancient Greeks believed that it had the power to increase a person’s strength and make its wearer invisible. Topaz was also said to change color in the presence of poisoned food or drink. The gem’s mystical curative powers waxed and waned with the phases of the moon. When the powdered stone was mixed with wine, it was considered a cure for asthma, insomnia, burns and hemorrhages.
Yellow Topaz strengthens faith and optimism. It assists in recognising your own abilities, and can attract helpful people to assist you in your endeavors.
It bestows charisma and confidence with pride in ones own abilities. Yellow Topaz regenerates cellular structures and is beneficial in relieving nervous exhaustion through stress. It can help increase blood circulation, and can influence the function of the liver, gallbladder and the endocrine glands, as well as relieve pain associated with disorders in these areas.
It is highly energizing and warming. It is used to stimulate the intellect; it aids abstract thinking and creativity by bringing forth ideas from the mental level into concrete form. It is said that one can place a Golden Topaz in the home to protect against break-ins and fire.
Topaz is the hardest silicate mineral found in nature. It is a silicate of aluminum, and contains about 20 percent water and fluorine.
The relative proportions of these impurities are responsible for the color variations of the stones. Crystals with more water are yellow to brown, while those with more fluorine are typically blue or colorless, like aquamarine.
some of the info sited here was also gathered from http://www.neatstuff.net