What makes one specimen better than another

There is no grading standard in this craft. There is a set of criteria everybody uses and nobody has written down identically.

Six things, in rough order

Damage. Complete and undamaged beats everything else.

Crystal quality. Sharpness of form, lustre, transparency, color saturation.

Aesthetics. How the specimen is composed: position on matrix, balance, whether it has a front.

Rarity, of the species, of the habit, or of that quality from that locality.

Locality. A classic locality carries a premium over the same material from an unknown one.

Size, last, and mostly through its interaction with the others.

Damage is the first question

Because it is binary in a way the others are not. A contact, a surface where the crystal grew against something, is natural and acceptable. A break is not.

Look at every termination, every edge and the back. Rotate under a light. Damage hides on the side that was against the dealer's cloth.

And disclose it when you sell. Every experienced buyer checks, so undisclosed damage is not a saving, it is a returned specimen and a lost customer.

Aesthetics is real and not measurable

Two specimens can be equal on every objective criterion and differ substantially in price because one is composed and the other is not.

That is not irrationality. Most specimens are bought to be looked at, and how something looks is what is being bought.

It is also the criterion that takes longest to develop, and the one that is worth developing by looking at good material at shows rather than by reading.

Grading consistently

Write down what you mean by your own terms, what is "fine", what is "good", and apply them the same way twice.

Grade against reference specimens rather than against memory.

And grade in the same light. A specimen judged under a halogen spot and one judged in daylight are not being judged on the same criteria.

References