The diamond is unique among all gemstones and that is because it is made of only one element-carbon. Its crystal structure or lattice is so strong that only elements such as nitrogen, boron, phosphorous, hydrogen and such metals as nickel and copper can intrude into its structure during its growth. It is also the hardest mineral in the world, that is why, it is held as the most valuable and most romantic stone in the world.

The purchase of a diamond ring is the most important occasion in a man's life and to the girl who is to receive it. Picking out a good quality diamond jewellery amongst the many beautiful, sparkling ones requires careful consideration. Select the best and highest quality by considering the four factors that determines a diamond's quality.

1. Colour

The intrusion of such elements as nitrogen, hydrogen, etc., gives the yellow, brown, blue, pink and whatnot colours to this otherwise colourless gem. The purest diamond is of course without colour and appears totally white, but no such diamond exists. Most white diamonds have a yellow or brown tinge caused by nitrogen.

As such, yellow or brown hued diamonds are cheaper than other hued or white diamonds. But if the diamond is an intense yellow or brown, its value goes considerably higher as well. But intensely coloured ones are very rare and are mostly found lodged in museums. There is a colour grading given to diamonds with the totally colourless having the top grading of D. The grading then goes down, by degree of colour, to F, G, and so forth. So ask what colour grade the diamond jewellery your eyeing has.

2. Clarity

Impurities can mar the beauty and quality of diamonds. Deformities in the diamond's lattice structure that leave a tiny inner crack can also do this. Such imperfections called intrusions which appear whitish or cloudy can affect the clarity of the diamond, especially if the intrusion is visible, noticeable or quite many. Clarity grading is affected by such intrusions. So make sure to check for tiny cracks or cloudy elements in your diamond. But as long as these intrusions are not detectable to the naked eye, you may breathe easy; its clarity will not be affected.

3. Carat

A jewel's weight is measured by carats. One carat weighs 200 milligrammes (mg), and is considered as 1 point (0.01) under the point system that is used for diamonds that is less than 1 carat. Of course, price goes up the higher the carat. The bigger the diamond, of course, the higher its price as the market demand for size is very high.

4. Cut

Cutting a diamond is an art and a science. It shows the skill and workmanship of the jeweller and the angles to which the diamond is cut. The principle behind a diamond's particular cut is finding the ideal shape for the stone to return and scatter light, or facets, when it is viewed from above. How a diamond sparkles and displays such brilliance has to do with how well it has been cut. Diamond cut is not to be confused with its shape.