Gemstones are described by gemologists using technical specifications. Gems have refractive index, dispersion, specific gravity, hardness, cleavage, fracture, and lustre. Some minerals that are too soft to be generally applied in jewelry may still be considered a gemstone because of their remarkable color, lustre or other physical properties that have aesthetic value. Crystals and gemstones are a marvel of nature- in there perfect geometrical structures. Only five types of gemstones were considered precious: diamond, ruby, sapphire, emerald, and amethyst.

A gemstone, gem or precious /semi-precious stone is a highly attractive and valuable piece of mineral, which when cut and polished is used in jewelry or other adornments. Although the different stones formally have the same chemical composition, they are not exactly the same. Color is the most obvious and attractive feature of gemstones.

A diamond is a transparent crystal of tetrahedrally bonded carbon atoms and crystallizes into the face centered cubic diamond lattice structure. Toughness relates to a material's ability to resist breakage from forceful impact. The most familiar usage of diamonds today is as gemstones used for adornment. Television ads portray them as the ultimate gift of love. Magazine ads want us to believe that a diamond is the only perfect gift to express love. If you plan on purchasing a diamond because you like how it looks or if gives you or your love one pleasure then by all means buy it but also consider it as a form of investment.

Emerald is a variety of the mineral beryl, colored green by trace amounts of chromium and sometimes vanadium. The name emerald comes from the Greek 'smaragdos' via the Old French 'esmeralde', and really just means 'green gemstone'. Colombia continues to be at the top of the list in terms of the countries in which fine emeralds are found. The magnificent green of the emerald is a colour, which conveys harmony and love of nature. The value of an emerald depends on cut, color, clarity, and carat. The colours do not occur until traces of some other element are added.

A Ruby is a red variety of the gemstone corundum, the color caused mainly by chromium. A ruby appears red because it absorbs all the other colors of white light - blue, yellow, green, etc. The fewer the number and the less obvious the imperfections, the more valuable the ruby is. Although pieces of red corundum can be found weighing many kilograms, they are generally not of sufficient quality to be valuable as gemstones.

Sapphire is the non red variety of the mineral corundum, an aluminium oxide. Some natural sapphires can be found as completely transparent, or "white. Sapphire includes any gemstone quality varieties of the mineral corundum except the fully saturated red variety, which is instead known as ruby. The value of a star sapphire depends not only on the carat weight of the stone but also the body color, visibility and intensity of the asterism. Color changes may also be pink in daylight to greenish under fluorescent light. Australia leads the world in sapphire production.

No matter the gemstone they look best in jewellery, which uses gold as a base. Although the price of some platinum group metals can be much higher, gold has long been considered the most desirable of precious metals, and its value has been used as the standard for many currencies (known as the gold standard) in history. Blue gold can be made by alloying with iron and purple gold can be made by alloying with aluminium, although rarely done except in specialized jewelry. Alternative white gold alloys are available based on palladium, silver and other white metals (World Gold Council), but the palladium alloys are more expensive than those using nickel.