The Maha Naag Mani is considered as one of the nine sacred pearls (Nava Moti) and most of the books on gems give the procedure how it is formed, ie when rain drops in Swaati Nakshtra into mouth of the king cobra, the Geliga Naja Mani develops. Books also mention that it only happens in the cobra that passes one hundred years of life on earth. Once the naga gem pearl is formed the snake achieves magical powers and can transform into any form it desires, the size and lustre of real nagamani stone increases with age of snake. It is moon like pearl called nagamanickam stone with green tint and it emits light in darkness to play with it and to search for its prey in its light. Owning such Mani, leklai for sale, is considered good luck, makes person wealthy and fulfil all desires. It also mentioned that when fish pearls like green gem is separated from the Cobra, the cobra dies. There are various types of Naga Mani which may be called stones of a snake or snake stones aka snake gems. As regards emission of light, there are some snake stones or gems which emit light at will and some stones that won’t emit any light. The legendary Naag Mani shown in an artistic viewpoint as a big ruby type red gem atop the hood of king cobra is not seen or available anywhere. Most snake charmers and those who deal in these items say that the growth of light emission is proportionate to the age of the snake and the stone from a younger snake do not possess that much light as that of an old snake gem, so Naag Mani which are genuine from snakes but are not old enough or grown enough do not emit enough light yet they are rarest to get.
But the real truth is, that this greenish coloured light emitting glow in the dark snake gems called nagmani, absorbs light first and emit and glow in the dark. It absorbs and releases light, again the same procedure and so on. It cannot glow always as it dims over the time as it loses its stored light.