Are there any types of gems or jewels that spontaneously give off light??

Answer 1

That's an interesting question! And the answer is YES!

Some gemstones do "give off light" but usually at wavelengths that the human eye cannot normally pick up. We have to use ultraviolet lights or filters to help us see the stones fluoresce.

There are around 4,000 different types of minerals - approximately 15% of them are known to fluoresce. Impurities in the mineral (usually) cause this fluorescence. These impurities -called “activators” - are the reason for different colors. Known activators include: Manganese, Chromium, Iron, Titanium, Copper, Lead, Europium, Cerium, Uranyl, Tungstate, Molybdate, Sulfur, Nitrogen, and various Organic activators.

The presence of an activator does not mean the mineral will fluoresce - different minerals with the same activator may even fluoresce different colors. Some activators require another “co activator” to cause fluorescence, and some impurities will prevent fluorescence.

Have you ever wondered why a good red ruby always seems "punchier" than a good red garnet? Why one diamond seems so much whiter than another even though their grading report is the same? Fluorescence? Although it's not supposed to be normally detecable by the human eye, isn't it rather coincidental that fine rubies almost always have a red fluorescense and good white diamonds, a blue one?

Some examples of stones that fluoresce: Rubies, Spinels, Diamond, Scheelite, Calcite, Fluorite etc.

Answer 2

As in internally give off light? None.