Gems I: Types

I ended the first post of my series on gems (Gems Intro,) with this paragraph:

I plan on detailing each of these modified steps in a separate post, with appropriate tables. I won’t be posting before next week, however.

That was four years ago, so I was right.

Part of the reason for the delay was that I had finished (or nearly finished) the next part, but then lost all my draft posts, somehow. And after I found them again last month, I had to review what I’d written to figure out what I was aiming for. Also, I’ve changed my mind on some things, so I had to rewrite parts of it. But basically, my first post laid out three or four steps for generating gems in a pile of treasure.

• Steps Zero and One: Pick a Dungeon Theme and Gem Types to Match
• Step Two: Roll for How Many Gems Are in Each Treasure Trove
• Step Three: Assess Each Gem

Step One happens before stocking individual rooms, Step Two happens when stocking the rooms, and Step Three happens during the game session.

But Why?

What are my basic goals for making new gem rules?

I want two or three things:

• To reduce the amount of information that needs to be tracked per gem,
• To simplify and compress the generation process,
• And maybe to make it easy to improvise without actually looking at a table?

Reduce

There’s really only about eight or so gem names people are really familiar with: diamond, emerald, jade, opal, pearl, quartz, ruby, sapphire, maybe a couple others like jet, topaz or turquoise, but not everyone’s going to be able to recognize the same batch and most of the others are just different types of quartz, anyways. So recording gem names or being meticulous about base values for each type seems like a waste.

Instead, I say: reduce gem information to just Size, Color, Opacity, and Miscellaneous. The first three can be written in a single keyword, like “Xb5”. “Miscellaneous” only pops up if you want a gem with a special (magical?) ability.

Recycle

I’ve used Roman numerals before for things like size categories, so of course I’m going to do that again. We only need V, X, L, C, D, M, because who cares about Size I, anyways? And the hard part of Roman numerals is counting and subtracting, but we only need one letter per gem code. Here’s a table we only need to read once and never need to look at again.

Numeral	Size Reference	Default Gem Value
V	bead-sized (small)	5 coins
X	pebble-sized (small)	10 coins
L	marble-sized (med)	50 coins
C	eyeball-sized (med)	100 coins
D	egg-sized (large)	500 coins
M	fist-sized (large)	1000 coins

Reuse

One thing I use a lot is a simple d6 “table” for adjusting values on just about anything:

d6 roll	adjustment
1	move value down one
2-5	no adjustment
6	move value up one

You don’t even really need a table for this. It’s just “lowest possible result = down one, highest possible result = up one”.

I also like to use dice positions, reading left to right, to roll multiple things at once. I can reduce the number of rolls that way and speed things up immensely.

Building the Dungeon

I suggested that GMs creating a dungeon key should pick a small number of gem types for their entire dungeon. Specifically, I suggest three or four gem types per dungeon, with a color scheme that matches the dungeon’s theme. One gem will be the low value gem, a second would be the middle value, and the third would be the high value. If necessary, a fourth type matching either the low or middle value, but with a different color, opacity, or additional feature like a glow can be added when it’s thematically appropriate.

If you don’t have an idea what color you want your gems to be, just use the rainbow colors (Roy G. Biv.) Start on yellow for the low value, green for the mid value, and blue for the high value. Roll 2d6 and read the dice individually, left to right.

• First d6: 1 = shift values left one color, 6 = shift values right one color
• Second d6: 1 = shift low value gem down, 6 = shift high value gem up

Size

The default gem size for a given dungeon is based on deepest dungeon level / 2.

Level	Gem Size
1-2	C
3-4	D
5-6	M
7+	3M

This is for the high value gems. Low value (common) gems will be two sizes smaller by default (X to D.) Mid value gems will be one size smaller. Values above M use an Arabic numeral multiplier: 3M, 5M, 10M, 30M, 50M.

Roll 3d6 in order and read the dice individually, left to right.

• First d6: 1 = shift all sizes down one, 6 = shift sizes up one
• Second d6: 1 = shift low value gem down one size, 6 = shift high value gem up one size
• Third d6: Opacity

Opacity

Opacity is recorded as an index value (9 = 90% opaque, 5 = 50% opaque, 0 = less than 5% opaque.)

The third d6 rolled is the base opacity for the high-value gem, treating a 6 as zero. For mid-value gems, add +4. For low-value gems, add +8. Opacity is capped at 10, which is completely opaque.

Opaque gems are the listed size for their size value, but murky, translucent, or transparent gems will appear smaller.

• Opacity 0 to 2 reduces apparent size down two steps without reducing the value.
• Opacity 3 to 7 reduces apparent size down one step.
• Opacity 8+ is the listed size.

Gem Codes and Names

So let’s say you’re making a four-level dungeon. You start with the default gem colors of yellow, green, and blue, from low value to high value. You roll 3d6 and get (6, 4, 2). How do you write this in your notes?

• The low value gem is Cy10, an opaque yellow gem the size of an eyeball.
• The mid value gem is Dg6, a murky green gem of the same size, despite being worth 500 times as much as the low value gem.
• The high value gem is Mb2, a translucent blue gem that’s also the size of an eyeball, but worth 1000 coins.

The actual values of the gems can vary up or down during both the next step (stocking treasure in rooms) and the final step (getting the gem appraised.)

But what about the names? Unless a particular gem sounds like a diamond, sapphire, or emerald to you, I think you should stick to fantasy gem names specific to your world. Opaque yellow gems the size of an eyeball might be known as “Ra’s Eye gems”. Murky green gems might be “mossmist gems”. These names wouldn’t be listed in the dungeon key, but on a “list of gems in this world”, which you would build as you expand your campaign.

When players discover these gems, however, they won’t get the gem names or values immediately. Instead, just say "three small translucent blue gems, a few small murky green gems, plus a whole bunch of small yellow stones.

But more on that in a future post.

Series Index

• Gems Intro
• Gems I : Types (this post)
• Gems II : Quantities
• Gems III : Assessments

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