Specimen vs Rough Material

We're working on downsizing right now and I feel your pain. We aren't really specimen collectors so much, most of the ones we have are either self collected unique curiosity rocks of little value or pieces that we found in estates for so much less than they were worth that we grabbed them. Most of what we're dealing with is several tons of rough and thousands of slabs that would take several full lifetimes to get to. The idea is that when I turn rough to slabs I generally increase the value 2x to 5x, so $25/lb rough makes more sense than $5/lb, and same with cabs. The saws are running as full time as possible, don't plan to take all 6 big slab saws with us.
We have been realistic in our approach IMO, started having a couple sales a year about 3 years ago. The thing I have noticed about that type of sale is that every time you go the pickings get sketchier. Our approach has been to start by only separating the least valuable material the first time through, and downgrading our leftovers each time. This spring we will donate a bunch to the club and the Rice Museum of Gems and Minerals, then take a trailer load or so the the club show in May as vendors, then possibly again in Prineville in June, each time with better materials than the previous time. In July whatever we keep goes into a 40 foot (or 28' if we're able) container along with any equipment and such that we decide to keep and it all goes to our new home, hopefully just enough to keep us busy for the rest of the time we are able to do it.

What everyone else said. I'd add that for things like jaspers and agates that don't have a visible crystalline structure, using endcuts that preserve part of the outer surface (rind, angelwing, etc.) make great specimens, while allowing you to take slabs. For petrified wood, full, thick rounds fetch higher prices. For mineral specimens, unworked pieces that have good examples of the crystal's structure and how it grew (side faces, terminations, and even attached matrix host) are the most desirable, though that isn't possible with every mineral type. For some rarer minerals, even tiny micro-mount and slide-mount partial crystals can carry high prices.

For your unique and unusual items, do consider mounting and labeling them for display pieces so they are easier for you to enjoy. I find mounting and labeling to be relaxing in itself, and something to do with rocks when I cannot get out much. Nature's art deserves the same respect as man-made (or more, in the case of much of it), and just like a nice frame can set off a nice painting, or mounting on a plinth a sculpture, presentation can elevate your specimen from something found in the back of a drawer to a dramatic piece that sparks people's interest. FWIW, some ideas...

For multiple slabs, I look at the closeout tables at stationery stores for wire letter holders:

Easel stands for single slabs are available from rock shops and similar (or you can scout thrift stores for plate/saucer holders or easels used for small framed photos that work just as well), but when you get a bunch of slabs that are dear to you and run out of shelf space for individual slabs, the letter holders allow you to free up some space.

They make beveled stands for spheres, marbles, and ball-like rocks (concretions, thundereggs, geodes, etc.), but sections of pipe work just as well and are MUCH cheaper:


For large specimens, you can ask at home improvement/tile/countertop stores for discontinued sample squares of granite, marble and other stones. They are already polished, and you can just glue a piece of felt to the back for a nice place to park a piece that doesn't scratch your wood shelves or tabletops. Looks very museum-like in person:


Really small crystals, or even some cut gems, are best put in micromount boxes. Several types out there, and not expensive. Be sure to get some mineral mounting tack/putty at the same time (a little goes a long way, doesn't stain and is removeable):


Larger crystals can be mounted (using mounting tack/putty) on a square of acrylic or tile:


Larger display boxes can be spendy, but you can group multiple small, related specimens together:


For ultra-rare crystals that only come in nearly microscopic sizes, the traditional way to store and display is to use gelatin capsules. However, I personally prefer to put them on an adhesive dot inside the lid of tiny specimen jars (groups of these can be displayed, labeled lid up or down, in a small box). The lid can be unscrewed for viewing under a microscope camera:


For tiny/thin sliced sections, mounting them on glass microscope slides is probably the only option, but those don't make very exciting displays. You can print labels on ordinary printer paper (an acid-free paper is best, as it doesn't yellow) and use a non-puckering glue pen (I like the ZIG brand) to adhere. I use a fine-tipped paint pen to label the backs of slabs (and sometimes the bottoms of rougher pieces that have a somewhat smooth area). Maybe these will give you some ideas of your own.