Years ago, I wrote an article about how I use gems in my game. Apparently, it was poorly written and people found it confusing. I’d like to take the opportunity to revisit that one, and see if I can do a better job of expressing myself.

In the real world, gems are very small and extremely valuable. A small diamond (~ 5mm) may be worth thousands of dollars. Despite its value, I can practically hear the crotchety old dwarf, having searched the bad guys that they just defeated in an epic battle, yelling “This is it? Pebbles!?! All that work for a couple of bleedin’ pebbles”?

That isn’t how I want to envision gems in my fantasy games. There are movies where you see treasure chests brimming with gold, silver, goblets, necklaces, crowns, and (most spectacularly) handfuls of gems (diamonds, rubies, emeralds, and sapphires) the size of marbles (and larger). That is a treasure befitting a fantasy story.

The problem is that if you apply real world values to fantastic gems like those, you end up with a treasure chest full of booty so valuable that the entire party can live like kings for the rest of their lives. That doesn’t leave much incentive for further adventuring, not to mention the devastating effect on the local economy.

What I want are large gems worthy of the swashbuckling tales that I remember, but are inexpensive enough that they don’t cause an imbalance. So, what does that mean exactly?

I want common items (combs, hairbrushes, hand mirrors) set with tiny stones (maybe ¼”), just for flavor, that add almost nothing to the item’s value. If you rob a noble’s house, you wouldn’t expect to find plain ordinary items. These personal items should be a step up from what the average person might have, but the actual value of such items should be relatively inconsequential.

I want tiaras and crowns, and similar pieces of jewelry, to have larger (and better quality) gems (maybe ½” – 1″ diameter), befitting the station of the person who would wear such things. These gems, being larger, would have a little value associated with them. But again, let’s reign in that value. The base item would have tens to hundreds of GP worth of materials. The workmanship or significance of the item might raise the value tenfold. I’d like to add a significant number of gems without raising the cost more than an additional 50%.

But where I’m really going with all this relates to enormous gems, the size of the one on the cover of the PHB. It is one of a pair of giant rubies (at least the size of your fist), that the thief is prying out of the eye of the idol. I want my adventures to include gems like that (on rare occasions) that represent a significant amount of money, but also a limited amount of money. It should be cause for celebration, but not enough to retire on.

Now, with a frame of reference, it is time to define the gems that fit my criteria. As you can see in the following chart, I have defined “average” gems to be 1″ in diameter (a very substantial gem!), with larger and smaller stones doubling or halving in size at each size category increment.

Note: Some of you will notice that a stone 2x as big won’t weigh 10x as much (it should be 8x, which would make record-keeping more cumbersome). To get a 10x weight difference, the actual size difference would be the cube root of 10 (~2.15), but I’m going to fudge the numbers here. Also, different gems have different densities so gem weights listed here are entirely a fiction of convenience anyway.

TinySmallAverageLargeHuge
Diameter0.25″0.5″1″2″4″
Weight (pounds)0.00050.0050.050.55
Gems per Pound2,0002002020.2
Common Stones*1 cp1 sp110
Ornamental Stones1 cp1 sp110100
Fancy Stones1 sp1101001,000
Precious Stones1101001,00010,000
Gem Stones101001,00010,000100,000**
Jewels1001,00010,000100,000**1,000,000***

* Tiny Common Stones have no value.
** Gems with a value over 10,000 gp are extremely rare and may be difficult to sell.
*** Such legendary gems probably don’t exist.

I think the above chart meets my requirements nicely. It isn’t a huge change from the original 1e description of gems, but it makes some changes that I think are important. Small intimate items would be set with tiny ornamental stones (1cp each). Jewelry would be set with small to average size fancy stones (1gp – 10gp each). A ruby “eye” the size of your fist (~4″) would be a huge precious stone (10,000 gp).

I’m pretty happy with it. This allows for an overabundance of gems without unbalancing the game. High-end gems still make a convenient way to carry around large sums of cash, but enough gems to represent any vast amount of cash now becomes more difficult to conceal (an unstated goal of this exercise). Substantial treasure items can get a boost from adding a few mid-range gems, and lesser gems can add flavor to minor treasure items without overly affecting the price. Best of all, you don’t need a magnifying glass to see what sort of loot you’ve got.