So which is better? one pound of gold or ten pounds of gold? Ten pounds, of course. But how much better? Well, ten times better.
OK, which is better, a one carat diamond or a ten carat diamond? Ten carats of course. But how much better? Well, FIFTY times better! No really! When you are talking about things that cannot be joined together (like melting gold down to make bigger pieces), bigger (typically rarer) sizes are not just more valuable, they are hugely more valuable.
So what does this affect? Well, all of the gemstones to start with, but there are more than just that. Things like gemstones are also affected. Things like pearls. One of the best examples of this in Fletnern is the substance known as chrystalist. Chrystalist is the only known substance that makes safe mentalist talismans. So in order to make bigger and better talismans, you need to be able to carve more enchantments into the piece of petrified whatever it is. So bigger pieces are vitally important.
But that’s still sort of a gemstone. What else? Well horns, or more commonly tusks. There are tons of things that can be made out of small pieces of ivory, but when you want the gateway to your camp to be two huge elephant tusks of gleaming ivory, you need full tusks, not broken pieces. And bigger is better. Getting the tusks off of some three year old cow is not the same level of importance as getting the tusks off of a thirty year old bull.
Last one: parchment. The parchment you can make out of a lambskin is significantly smaller (and therefore less valuable) than what you can get from a full grown steer. Not as impressive as the diamond, but an important example nonetheless.
What you are really paying for here is rarity. Not only are diamonds rare, but big ones are vastly more rare than tiny ones. Big unicorn horns are far more rare than smaller ones, and intact ones are more rare than broken ones. The rarer something is, the more expensive that thing is, assuming that you cannot just join things together. Even when you can join things together, like building a marble altar, having huge pieces so there are no seams will make the bigger pieces that much more desirable and expensive.
When does it matter? It matters when the adventuring party recognizes that the altar stone of the subterranean temple they just ransacked is made of rare marble, but the piece is so big, that they can’t carry it. Cutting it to manageable pieces is going to dramatically reduce the value. Is it worth transporting the huge block of stone? It is important when you steal the king’s scepter and there is a 50 carat ruby on the end of it. Sure, the ruby is worth a king’s ransom, literally, but trying to fence an object that is obviously stolen from the king is incredibly dangerous. Do you cut it into smaller rubies in an effort to hide what it once was, knowing that you are losing a huge amount of wealth? I like putting problems like these in front of my adventuring parties. I think it’s fun to make them think about strategy outside of battle.