A custom acrylic display easel, designed specifically for minerals. These are the same stands I use myself at shows, and are great for large cabinet samples. As an example, the specimen in the picture (not included) weighs nearly 3 lbs and is about 16 x 12 cm-- and the stand is perfectly stable and having no issues supporting it.
These are much better than the stands designed for plates or generic collectibles-- they tend to be minimally visible, and their geometry allows them to hold specimens much more stably than others I have tried. They wont work for all pieces, but again, I have tried most of the commonly available stands and these seem to have the widest utility.
Sold as a single unit for $5., or in sets of 10 for $45.