Man has been carving rock and minerals since prehistoric times. In fact a prehistoric time period, believed to have begun somewhere around 2.5 million years ago, is known as the Stone Age, because during that time period man learned to use stones to make their tools and weapons.
I do not know when the first gemstone egg carvings were done. I do know that throughout time the egg shape has symbolized birth, spring, and new beginnings.
Many religions view the egg as a symbol of growth, protection and resurrection. Rituals often use rock eggs to promote fertility. Clay eggs have been found in prehistoric graves and the Ancient Romans began the tradition of decorating eggs to celebrate the vernal equinox, also known as the spring equinox or the first day of spring. It was a time of renewed hope for people who had made it through a difficult winter. And of course now of days the egg is an important part of spring and Easter.