The most common sulphide that I have seen is the white porcelain figure in crystal glass. There are some variations of sulphides out there, and they can be pretty rare.
Hard-to-find sulphides that have colored glass (like green or blue), and the figures in the marble can sometimes be painted.
Another thing to keep an eye out for are different figures. More common sulphides feature a dog or cat. Sulphides that feature a deer, lion, pig or even a bear command a bigger price. Human figures are also rare as well. Numbers are also been known to show up as well. Usually, it’s a single digit.
There are two things to keep in mind when it comes down to the condition of the marble. The glass itself is always something to look at for chips, cracks, and even clarity. But don’t forget to examine the figure itself.
When the marble was made, it was made by hand. The figure was inserted into the molten glass, and then the glass was formed into the final shape. When the figure was inserted into the glass, it could crack or an air bubble could form right beside it. The crack is usually obvious, even to the naked eye. I have even seen figures completely split in half.
You can find plenty of modern sulphides for sale. The difference in new and old sulphides are very obvious. The new sulphides have an extremely high quality on both the glass and the figure. The figure will always be perfectly centered. They were meant to be collected and displayed.
Old sulphides will have air bubbles in the glass, and the figure will be off-centered and sometimes there will be a pontil mark. They were meant to be played with, and they often were. Sometimes they were played with to the point where they are chipped and even cracked.
There is an authentic antique sulphide marble in my Etsy store; you can see it here.