The 4 C's

Beauty of gems
Although it is not one of the 4 C's,cleanliness affects a diamond's beauty as much as any of the 4 C's (cut, carat, colour, clarity).
A clean diamond is more brilliant and fiery than the same diamond when it is "dirty". Dirt or grease on the top of a diamond reduces its lustre. Water, dirt, or grease on the bottom of a diamond interferes with the diamond's brilliance and fire. Even a thin film absorbs some light that could have been reflected to the person looking at the diamond.
Coloured dye or smudges can affect the perceived colour of a gem. Historically, some jewellers' diamonds were misgraded due to smudges on the girdle, or dye on the culet. Current practice is to thoroughly clean a gem before grading its colour as well as clarity.
Cleanliness does not affect the jewellery's market value, as jewellers routinely clean jewellery before offering it for sale. However,cleanliness might reflect the jewellery's sentimental value: some jewellers have noted a correlation between ring cleanliness and marriage quality.
Methods and risksMaintaining a clean diamond can sometimes be difficult, as jewellery settings can obstruct cleaning efforts, and oils, grease, and other hydrophobic materials adhere well to a diamond's surface. Some jewellers provide their customers with sudsy ammonia cleaning kits. Many jewellers use steam cleaners. Some other jewellers sell small ultrasonic cleaners. Home-based cleaning methods include immersing the diamond in ammonia-based or ethyl alcohol-based solutions, or even a solution of mild grease dissolving detergent and warm water. Silver jewellery can be cleaned using aluminium foil, baking soda, and hot water. However, this practice is not recommended by most jewellers.
Certain types of cleaning can damage some jewellery. For example, some class rings are coated with a dark pigment to reduce their shininess. Some gemstones, such as white topaz, have an overlay to produce certain colours. Ultrasonic cleaning can remove this coating, if it is not a quality piece. Ultrasonic cleaning is also contraindicated for opals, pearls and amber, and any other gemstone that is porous. Gemstones that are glued in (a common practice with semiprecious stones in non-precious methods, and in class rings) should not be placed into an ultrasonic cleaner. An ultrasonic cleaner can cause stones that are loose in their settings to come out. Jewellery should always be examined for overlays and loose stones prior to cleaning with an ultrasonic cleaner or a steam cleaner.

Amber

Amber is the name for fossil resin or tree sap that is appreciated for its colour. It is used for the manufacture of ornamental objects and jewellery. Although not mineralized, it is sometimes considered a gemstone. Most of the world's amber is in the range of 30–90 million years old. Semi-fossilized resin or sub-fossil amber is called copal.
The presence of insects in amber was noticed by the Romans and led them to the (correct) theory that at some point, amber had to be in a liquid state to cover the bodies of insects. Hence they gave it the expressive name of suceinum or gum-stone, a name that is still in use today to describe succinic acid as well as succinite, a term given to a particular type of amber by James Dwight Dana (see below under Baltic Amber). The Greek name for amber was ηλεκτρον (Electron) and was connected to the Sun God, one of whose titles was Elector or the Awakener.
The modern term electron was coined in 1891 by the Irish physicist George Stoney, using the Greek word for amber (and which was then translated as electrum) because of its electrostatic properties and whilst analyzing elementary charge for the first time. The ending -on, common for all subatomic particles, was used in analogy to the word ion.
Heating amber will soften it and eventually it will burn, which is why in Germanic languages the word for amber is a literal translation of burn-Stone (In German it is Bernstein, in Dutch it is barnsteen etc.). Heated below 200°C, amber suffers decomposition, yielding an "oil of amber", and leaving a black residue which is known as "amber colophony", or "amber pitch"; when dissolved in oil of turpentine or in linseed oil this forms "amber varnish" or "amber lac". As mentioned above, amber was well known for its electrostatic properties since antiquity (though not identified as such until the concept of electronic charge became clear).

Gemstones

Gemstones are described by gemologists using technical specifications. First, what is its chemical composition. Diamonds for example are made of carbon (C) and rubies of aluminium oxide (Al2O3). Next, many gems are crystals which are classified by their crystal system such as cubic or trigonal or monoclinic. Another term used is habit, the form the gem is usually found in. For example diamonds, which have a cubic crystal system, are often found as octahedrons.
Gems are classified into different groups, species, and varieties. For example, ruby is the red variety of the species corundum, while any other color of corundum is considered sapphire. Emerald (green), aquamarine (blue), bixbite (red), goshenite (colorless), heliodor (yellow), and morganite (pink) are all varieties of the mineral species beryl.
Gems have refractive index, dispersion, specific gravity, hardness, cleavage, fracture, and lustre. They may exhibit pleochroism or double refraction. They may have luminescence and a distinctive absorption spectrum.
Material or flaws within a stone may be present as inclusions. The gem may occur in certain locations, called the "occurrence."

Sapphire

A sapphire means blue in Greek.Sapphire refers to gemstone varieties of the mineral corundum, an aluminium oxide, when it is a color other than red. Sapphire can be found naturally or manufactured in large crystal boules. Because of its remarkable hardness sapphire is used in many applications, including infrared optical components, watch crystals, high-durability windows, and wafers for the deposition of semiconductors, such as GaN nanorods.
The mineral corundum consists of pure aluminium oxide. Trace amounts of other elements such as iron, titanium and chromium give corundum their blue, yellow, pink, purple, orange or greenish color. Sapphire includes any gemstone quality varieties of the mineral corundum except the fully saturated red variety, which is instead known as ruby, and the pinkish-orange variety known as padparadscha.

The blue goes from dark blue almost black to pale blue. The finest blue sapphires are a strong blue. The star sapphire is very valued. Sapphires of colors other than blue are always referred to with the color. There are pink sapphires, yellow sapphires, violet sapphires, green sapphires and clear sapphires. Today most sapphires are mined in Australia.

Pink sapphire generates feelings of love, forgiveness, acceptance and release. This gentle stone provides strength in difficult situations.
This stone combines energies of the heart with a disciplined mind, creating strength in balance.
Pink Sapphire is a stone of passion that brings joyful play to any relationship.

Top-quality sapphires are rare Sapphires, call them gemstones of the sky though we may, lie well hidden in just a few places, and first have to be brought to light through hard work. Sapphires are found in India, Burma, Ceylon, Thailand, Vietnam, Australia, Brazil and Africa. From the gemstone mines, the raw crystals are first taken to the cutting-centres where they are turned into sparkling gemstones by skilled hands. When cutting a sapphire, indeed, the cutter has to muster all his skill, for these gemstones are not only hard. Depending on the angle from which you look at them they also have different colours and intensities of colour. So it is the job of the cutter to orientate the raw crystals in such a way that the colour is brought out to its best advantage.

Ruby

Ruby is a pink to blood red gemstone, a variety of the mineral corundum (aluminium oxide).
The common red color is caused mainly by the element chromium. Its name comes from ruber, Latin for red. Other varieties of gem-quality corundum are called sapphires. It is considered one of the four precious stones, together with the sapphire, the emerald and the diamond. Improvements used include color alteration, improving transparency by dissolving rutile inclusions, healing of fractures (cracks) or even completely filling them.
Prices of rubies are primarily determined by color (the brightest and best "red" called Pigeon Blood Red, command a huge premium over other rubies of similar quality). After color follows clarity: similar to diamonds, a clear stone will command a premium, but a ruby without any needle-like rutile inclusions will indicate the stone has been treated one way or another. Cut and carat (size) also determine the price.