In the old days, color and light were a much simpler concept to understand. There was natural light from the sun or synthetic light from lamps or fire. Nowadays there are many different sources of light and the options seem endless. Each light will give a different aspect to gemstones and it is important to find the most suitable light in which to grade and evaluate the stones in so that you can discover their true properties. As well as the countless types of light that you can use during evaluation, it is important to remember that a different light may be needed for a different type of gemstone. As well as different levels of brightness, light gives of altering color spectrums and in the gemstone business, the color of light as a function of its temperature is measured in Kelvins (k) which is higher according to the strength of the light and the level of red in the spectrum.

Colored gemstones are worthless without their color and it is very important that their color is judged and graded correctly before purchasing. The color of a gemstone arises from light interacting with the trace materials in the stone. In order for the light to interact with the stone, the light must contain all the colors needed in its spectrum. If the light source does not contain the specific colors then they will not be able to be seen correctly on the gemstone.

As people are becoming more aware of how light affects how we see gemstones, there are more options available from lighting stores that allow specific lamps and bulbs to be purchased for the use in gemstone evaluation. There is a wide variety of lamps available now, each with their own specific qualities which affect how they help to view gemstones. Incandescent lamps are not a good choice for evaluating gemstones as they are high up in the red color spectrum and low in blue, this will affect the color of the gemstone as you view it. Fluorescent lamps are available with a 'daylight' bulb which will imitate natural daylight and it is a good light for gemstone evaluation. The newest technology for lamp bulbs are LED, these are a great way to illuminate gemstones as they are low wattage and can imitate daylight in a natural way, without using a lot of power and energy, these lights are generally used in display cases.

The best way to evaluate gemstones will always be in natural daylight, this is not always possible and with all the altering environmental aspects that affect it. Using lamps with specific bulbs that will mimic daylight and can be set to different color grades and Kelvin strength allow evaluation to take place in any given place and with a higher standard for accuracy and precision.