I'm very new to stones and crystals, but really enjoying exploring them recently. Here's what one of my bookmarked sites has to say about gemstone eggs:
Throughout the ages, the egg has symbolized new beginnings, the spark of creation. Traditional folk religion regards the egg as a powerful symbol of fertility, purity and rebirth. Magic rituals often use eggs to promote fertility and restore virility (of the body and mind); and to foresee the future. Eggs mean growth, protection, new beginnings, resurrection. The Vernal Equinox celebrates the coming of spring and the egg is an important part of this ancient festival.
I guess it's true that eggs are connected with springtime in various ways. Many of us think immediately of Easter eggs (or Easter Island eggs, apparently...
), and the egg is also an integral part of the Passover Seder, and these are both important holidays that occur in Spring. Maybe gemstone eggs are therefore best used for meditations and magic work aimed at fertility, virility, purity, and/or rebirth/resurrection (sorry for all the slash-marks -- I <3 punctuation!).
So far, in my own personal collection, I have two items that could be deemed "egg-shaped." One is celestite, although it's probably not technically a true egg, in that neither end tapers more than the other -- it's more symmetrical, like a sphere that was elongated slightly along one axis, if that makes sense. The other one, a piece of rutilated quartz, is more truly egg-shaped, with one end narrower than the other. I bought the celestite because I wanted that particular kind of stone, and it was the nicest one of the bunch on sale in the shop the day I went -- I didn't buy it because I necessarily wanted something egg-shaped. Similarly, I got the rutilated quartz one because all they had were about half a dozen egg-shaped crystals, and then one big rough one that wasn't my style. The eggs jumped out at me because there's so much going on inside this particular kind of stone, and it occurred to me on the spot that it could be really cool to try scrying with one of them...so I bought the one I liked best. I haven't tried the scrying yet, but I aim to very soon (I also got a small gold sheen obsidian sphere for the same purpose, and I'm curious to see how successful I am with each one -- I'm a scrying neophyte).
So anyway, I was never seeking eggs per se, but I ended up with a couple! So far, the celestite seems like a very mild kind of stone, although whether that's due to this one's particular shape or just the general nature of celestite, my limited experience can't say. And then I can't speak to the rutilated quartz one just yet...