These two lights are very important in gemstone identification.
This is a normal light like sunlight and can be obtained by getting a lamp with fluorescent bulb.
This light is most needed in color change gemstones. This can be obtained by getting a torch or a lamp which has incandescent bulb. A good example is a candle light; it has the features and characteristics of incandescent light.
For you to see the color change in gemstones you must have an incandescent light. You can see the second color once applied on the gemstone. If the sapphire is green, once the incandescent light is applied it will change to pink or red.
In business another word for this incandescent light is “worm light”.