Back to IGS | FAQ | Contact

Artificial lighting for gems


Since incandescent bulbs are going the way of the dinosaur, is thre another type of lamp and/or bulb I can use to get a faithful replacement? Also, what kind of incandescent bulb should I be using? Thanks so much.'Diana


Hi Diana,
I fear there is no exact replacement. The incandescent bulb throws out a complete spectrum at about 2700K color temperature. You can use a “warm white” CFL as a replacement, but the fluorescent bulb does not give a complete spectrum, just some wavelengths in various areas of the spectrum which combine to give a white light. If you are looking at color change stones, there is no guarantee that the color will be the same in a CFL as it is under incandescent, even if the color temperature is the same. Likely to be the same, but I don’t think there is a guarantee. You may find a warm LED (which also throws out a complete spectrum) which duplicates incandescent, if the color temperatures are the same. It’s just that some areas of the spectrum are less prominent in the LED than in the incandescent. The LED bulbs I have throw a cooler light than incandescent, but I do think there are some LED bulbs which are warm white. Just look up the color temperature for an incandescent bulb on Google or get a spec sheet from the manufacturer and then look for an LED bulb to match that color temperature. That will get you the closest, although the warm white CFL may be close enough for your taste. All you can do is compare the various bulbs and see which match.
Hoep this helps,


You can use a Maglight with an incandescent bulb. It works well in the refractometer and for other lab tests. Also look on eBay and other online sources for incandescent bulbs that will fit household lamps they are available. I have one somewhere… lol … but normally I use fluorescent daylight equivalent. Yes the spectrum is different from sunlight but if you need a full spectrum like sunlight… try a window on a sunny day, or, take a plastic cup and cut a hole in the bottom, slide your Maglight in the hole and set it on your lab table pointed light side up. Using it for a spectroscope, cut a piece of black paper with a small aperture and tape it to the Maglight. Set your stone in the aperture and look at it with the spectroscope. Is there something else you need the bulb for?