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,