a Krayt Pearl Exceptional
Like Power Crystals, Krayt Dragon Pearls can be used to add damage to a Lightsaber. They can be looted from Krayt Dragons on Tatooine, and come in a variety of qualities. As with Power Crystals, the quality determines the damage range the pearl can add.
When a pearl is first looted, its damage modifier is not shown. A pearl must be tuned by a Jedi before you can see its stats. Once tuned, the pearl will only be usable by the Jedi that tuned it.
Qualities & Sources
Flawless - Up to 20 damage (None have been looted since before the NGE)
Premium - Up to 19 damage (Looted from Ancient Krayt Dragons)
Select - Up to 16 damage (Looted from Ancient Krayt Dragons)
Quality - Up to 11 damage (Looted from Ancient & Giant Canyon Krayt Dragons)
Good - Up to 9 damage (Looted from Ancient, Giant Canyon Krayt Dragons)
Fair - Up to 7 damage (Looted from Ancient, Giant Canyon, & Canyon Krayt Dragons)
Poor - Up to 5 damage (Looted from any Krayt Dragon)
Scratched - Unusable (Looted from any Krayt Dragon)
Cracked - Unusable (Looted from any Krayt Dragon)
Rumors
It has long been said that certain things can effect your odds of getting a good tune. Some say tuning near a Force Shrine, or having higher Luck, can result in better tunes. However, during the NGE conversion, it became apparent that crystals and pearls have set stats immediately upon looting them, they just simply are hidden until tuned.
There are also rumors that Flawless crystals and pearls can still drop. This is partially true, as Flawless were not removed from the loot tables. However, the reason Flawless stopped dropping is because Ancient Krayt Dragons used to be level 500. Now their level is considerably lower, making the odds of a Flawless dropping impossible.
There is also a rumor that pearls are stronger than crystals. This is untrue since the NGE. This rumor stems from pre-NGE when pearls and crystals had a speed modifier as well as a damage modifier. Back then, pearls had better odds of having a faster speed modifier, whereas crystals had better odds of having a higher damage modifier. When the NGE was released, there was a bug that left pearls with their speed modifier. For a short time, these old pearls were faster than new pearls and crystals. However the bug was promptly fixed and there is now no stat difference between crystals and pearls.
Some evidence shows that pearls tune on average 1 damage higher than crystals. However both crystals and pearls have the same tuning ranges. The higher average tuning is likely because it is very easy to hunt Krayt Dragon's specifically for pearls. Meaning most people hunt for pearls instead of crystals, making pearls tuned a lot more often than crystals.
Realism
While SWG displays Krayt Dragon Pearls as a milky white sphere, similar to pearls harvested from clams in real life, this is actually incorrect. While real pearls are formed by a clam encasing a grain of sand in layers of calcium carbonate (CaCO3), Krayt Pearls are formed by Krayts eating rocks containing crystals. Inside the Krayts gizzard, the rocks grind together, eventually wearing away all the minerals, leaving only the hard crystal behind. This crystal still looks like a normal transparent crystal, and behaves the same way once refined by a Jedi.
Other References
Knights of the Old Republic also had Krayt Dragon Pearls that added to a Lightsaber's damage. Unlike SWG, their appearance was more correct, the items description stating: "Taken from the gullet of a krayt dragon, this crystalline "pearl" appears to have refracctory qualities that might allow it to function as a lightsaber cystal once properly adapted."