Wednesday, June 15, 2011

It Occurs to Me ...

Mucking about with my trade and equipment tables this last week, and I have a few questions that have come up. For example, how large, exactly, are gems?

The AD&D Dungeon Master’s Guide says that every gem is between 1 to 5 g.p. weight, which for that silly system is one-tenth to one-half a pound, which would mean the smallest diamond you found as a player would be 1.6 ounces, or 320 carats, or a scant less than three times the size of the Koh-i-noor. It would be more than seven times the size of the Hope Diamond. In other words, truly ridiculous. Of course, for fantasy, it’s wonderous to think that every diamond is the size of a walnut (specific gravity of 3.52 for a diamond would make 1.6 ounces equal to 14.09 cubic centimeters, or about the size of a small plum), along with every other gem ... except, of course, that gems with a lower specific gravity, like spinel or amber, would have to be the size of a kiwi.

Executive Director of Jewels de Paragon, Pavana Kishore,
shows the Koh-i-noor diamond on
display at a Bangladeshi exhibition in 2002.
It would be a truly remarkable fantasy world if every gem that was ever found was automatically the size of a walnut or bigger. Unfortunately, it does make it difficult to make jewelry with walnut-sized gems ... often, something about the size of a pea is a little better for earrings and so on. A pea is still a pretty big diamond in this world, but yes, fantasy, blah blah, so let’s not go smaller than a pea, sweet mother of christ.
Unfortunately, a pea is only 0.27 cubic centimeters. This is fine for a diamond, which has a base price of 5,000 g.p. – as a pea-sized stone would be worth 95 g.p. – but it gets kinda sad for something like a zircon (base price 50 g.p.). A stone for a zircon earring would only be worth 19 s.p. Not exactly the sort of thing to make players excited. Ah, but then there’s a 1 in 10 chance the zircon could be worth 38 s.p.! Plus, a zircon necklace with sixty pea-sized stones would be worth 57 g.p. Oh, well, no worries, then.

I don’t doubt a lot of worlds would enjoy having these small cheap gems in great proliferation, and the players wouldn’t either, as long as they find three or four hundred of them in a good sized trove. The question is, how do you determine when the gem is pea-sized, and when it is the size of a walnut? Or, for that matter, when it’s the size of a marble, a cherry or an almond? And if you want to have a list for every size and kind of gem, how long is your equipment list going to get?

There’s another problem that I’ve always wondered about. If a garnet or an amethyst is 100 g.p. for a walnut-sized gem (letting that go for the moment), what about when the party stumbles across a geode? Does it just never happen? Because I have to tell you, for a geologist who is dedicated, these just aren’t that hard to come up with. My father found three, two ordinary quartz and one rose quartz) in the five years he was attending the Colorado School of Mines in Golden, back in the 1950’s when a lot of the back country of western Colorado was still unsurveyed. Just little ones, eight or nine inches across, but big enough to get one hell of a lot of stones out of them if the geode wasn’t too pretty to break up. I’ve seen hundreds of amethyst and garnet geodes out on display at various fairs, which seems awful common for something listed as ‘semi-precious’ in the books.

And as far as ornamental stones, I grew up swimming at a beach where we had to walk across a bed of stones to get to where the sand covered the lake bottom, and those stones were in large part either agate, quartz or quartzite. We used to pick out the pretty ones and tumble them, and they came out pretty much the same as the stones I’ve seen for sale in rock shops. My brother had one cut and set into a ring he wore for many years, and it looked as sharp as any agate ring I’ve seen. Seems to me, unless for some reason your world is remarkably short of quartz, the value of the ornemental stones listed is pretty high ... unless, of course, they all weigh half a pound, as gygaxian logic suggests.

Listen, these are just questions. If you’d like to tell me what I’m missing, I’d consider it a great help. I’m just thinking that if agate, which is common enough that the only value in the stone is the effort to tumble it (and it would have been harder in the medieval age, as we used an electrically-powered rock tumbler), how exactly does one decide where the rarity of the stone begins to outstrip the effort it takes to polish and prepare it?

Different subject, them. How much of the arrow, exactly, needs to be covered in silver in order to make it a ‘silver arrow’? Does the whole arrow need to be fashioned from silver? That doesn’t seem likely, since silver’s pretty inflexible and a fired silver arrow is going to fly about as straight as a frog. Can I still use goose feathers? Or is it only that the tip of the arrow needs to be covered in silver? It seems to me that if the shaft is made of wood and covered with silver, that silver is going to flake off when the wood flexes upon hitting anything solid, like bone. But if it’s only the head, which is expected to be metal anyway, that has to be silver, then I don’t see a problem.

Except, how then does one judge how much of any other weapon has to be covered in silver? If only the head of the arrow is necessary, can I just tip the points of my mace? If I tip the front edge of my sword for less money, do I have to roll every round to see if that part of the sword hit, or if I only struck the werebear with the iron part? What if I spackle my weapon with silver bits, or what if when it’s forged, silver is simply introduced into the general alloy? How much silver, exactly, has to be included in the alloy for this to work, and if it is 10% or some high number like that, won’t that make it more likely for the metal to give or break? Listen, it’s costing quite a sum of money to have this thing covered with silver. Surely its much more practical to use a silvered spear, where only the top inch (same size as the arrow which does the same amount of damage) than it would be to try and silver a sword. Right?

Okay, okay, how about this. If I have a suggestion spell, can I use it to suggest to one of my own players that they have nothing to worry about from me; and that if they lie on this table I’m just going to make a little break in their skin; and that they shouldn’t feel any pain as long as they don’t watch what I’m doing; so that if the spell is successful and they fail save, they can be blindfolded so that I can perform a heart-transplant surgery? I mean, if I have a couple of clerics standing by with cure serious wounds spells and a couple of cure light wounds and aid spells, and if I make all my dexterity checks, and I have another heart that a mage could maybe cast a change cantrip on to make it compatible with the player. It was, after all, usually the case that people died from surgery as a result of shock or infection ... obviously if the patient is calm and subject to the suggestion spell, I ought to be able to replace a bum ticker with a little experimentation on some local street urchins before trying the operation, right? Okay, the gentle reader is asking why, but I’m just suggesting that if every organ could be replaced from time to time, why not better organs and stronger organs and organs that were specially grown to increase blood capacity and so on in order to create a race of superbeings with nothing more than the spells I could get from 5th level or lesser characters?

I’m only asking.


2eDM said...

This idea is from an old Dragon Magazine article. The article had a list of charts with assigned values for each carat of a particular stone type, and that way you could then randomly determine the value of each gem the party finds. I seem to recall it also had a means of determining various gem-inlaid art objects as well. According to my notes, the article was called "A Re-evaluation of Gems & Jewelry in D&D" by Robert J. Kuntz in Dragon Magazine #8, in case you want to just go read the article yourself.

Zzarchov said...

In terms of Amethyst geodes I was always told that Amethyst was historically like Aluminium. Ridiculously rare until technology made it clear it was actually ridiculously common.

bighara said...

At the risk of pimping shamelessly, I feel like I should point out a relevant product:

The author put a good deal of thought into this very topic when writing it.

Carl said...

Your last paragraph reminds me of where my last Traveller game was headed. Vat-grown organs, genetically engineered super-beings, et cetera. At what point does fantasy become science fiction?

Alexis said...

Fantasy became science fiction when it included magic, vis-a-vis Arthur C. Clarke.

Big Rob said...

I was taught sci-fi was part of fantasy, but become popular enough to become its own genre.

Alexis said...

2eDM and bighara, I appreciate the suggestions, but of course they're virtually useless to me because of this. My system has to calculate the value of the gem from the ground up, based on the occurrence of the gem and its proximity to the market the player is buying from, or the lair the player is taking from. As such, my gems are never priced as even numbers like "500 g.p." It is entirely possible, if you are in the right place, to find rubies cheap and plentiful, or moonstones expensive and hard to find.

Oddbit said...

I would determine the loot. Price the gems based on weight. Give a weight of gems found. Divide by the average size and any remainder is a small gem for number. If they want specific sizes I would roll for variance within a specific upper and lower limit the keep the value 'the same' and assume no outliers. If they get a particularly large one, that means one of the other gems is particularly small. If there is only one gem plus the remainder, that would be an average sized gem.

Oddbit said...

For the silver, I would rule it is as much a ritualistic addition of silver as the amount of silver itself. However, yes, I would require the player only do the metal portions for a reduced cost on primarily wooden objects. (probably setting the silvering processes cost to a base cost + weapon cost X percent) Also if the player wanted to do half, I would have them either roll to determine what hit based on percent covered, or take a penalty to attack based on the only trying to hit with the silvered portion.

As for the replacing organs for creatures, I would basically politely ask my players to just seek out a regenerate as that's what it's for. That it was getting into the absurd region.

However... One can look at the amount of room for failure during the procedure rather than the use of a single spell. I'd even give the suggested player an initiative and play it out almost like a combat with the person in surgery starting in the negative hit points for such an intensive one. Also there would be skill checks and the heal spells would help stabilize, but healing too much would just plain close wounds. There would be a lot of complications that could occur and it would take some time to go through them. If they choose to make an encounter out of it by using that many spells I would make an encounter of it.

C'nor (Outermost_Toe) said...

So, if an amethyst the size of a walnut is worth 100 G.P, what's a geode 6-7 feet tall, and a 2-3 feet wide going to be worth? While ones like that are rarer, I know someone who owns a rock/jewelery shop and has something with those proportions, so they obviously exist. And, speaking of rarity, how do you calculate the increase in value as a stone goes up in size? Is it a linear progression, based on the base value and the weight given (plus the local rarity, but this is base value to calculate from), or is the fact that the larger ones are rarer factored in?


I'd probably only make someone coat the edges of a sword, or the tip of an arrow.

If they introduce it into the base alloy, then it would probably do less damage the less pure the silver was. Say 1/16th of the maximum for one percent, and increase from there?

This gets into vampires, too. How much of the stake has to be wooden?

Oddbit said...

With vampires and the average cost of wood I wouldn't tempt fate should there be a mistake. But I can see the issue coming up in deserts. Still, I would say the head would have to be wooden as well as whatever contacts the heart. This would be a piercing factor with the head and a contact factor with the heart.

(Note to self, put vampires in deserts)

Alexis said...


Then my mage in your world definitely wants to research the cantrip 'stitch' which does for flesh what the cantrip 'stitch' does for cloth - so I'm not closing up more that I want to close. Regarding regeneration, consider that its a very high level spell, and can only be performed once per day. With practice, I ought to be able to perform a dozen surgeries a day with the help of a few capable low-level clerics and mages, using them only when they're absolutely necessary, since we know these surgeries can be performed successfully without magic (of course, I don't have the chemicals I need, which is where the magic would have to suffice).

Consider, too, that once I have the format down, I can teach others how to do it, start an academy, create a powerful guild and ultimately win the favor of many kingdoms who would want me to bring my en masse healing to their people.

Different game tactic than mustard farming, I'd say.

Alexis said...


The increase in value as a stone goes up in size was a central element for me. A cherry-sized ruby weighs as much four marble-sized rubies, but the cherry-size is so much more rare that it can't just be measured as 4x marble-size. That rarity must be incorporated into the price.

2eDM said...

My apologies Alexis, I thought the question was more about size of gems, rather than determining value, hence why I gave the info about the article. I also seem to remember from back when I was working at a Jeweler's a few years ago that gems have always had a tendency to go in and out of fashion, so you could have a walnut sized diamond being worth less than a walnut sized piece of amber if diamonds were not all that popular in a location, but amber was.

C'nor (Outermost_Toe) said...

Quick clarification of terms: When you say "Marble sized" you're talking about the ones that you try to hit, not shooters, correct? (If not, I need to find some of those cherries...)

Alexis said...

Heh. Growing up, we used to call shooters 'boulders.' Right, I mean 'glassies,' which are classically 1.25 cm/0.5 in. in diameter.

C'nor (Outermost_Toe) said...

Thanks for the clarification!

Strixy said...

I think you'll need to account for a couple of other things.

Firstly, there are two distinctly different values for gemstones.Cut and uncut.

The process to facet gemstones wasn't really "common" in Europe until the 14th century. Gem cutting machines weren't introduced until late 14th century making faceted gems relatively more efficient to create. Egypt and India, however, developed gem polishing techniques 1,400 years prior to Europe. I'm not sure about China or East Asia.

That means, polished stones were more valuable than raw stones, cut stones were more valuable than polished stones and the availability of each is a function of the availability of crafts people to produce each.

The existence of cut gems in the 14th century were rather rare in Europe.

The quality of the cutters or faceters, was wildly disproportionate by population than most other trades. ie. there were very few. Even among those there were some few that really excelled at the craft, but many more who did not.

So that's the cut vs. uncut vs polished.

The ability of the faceter to create a quality and symmetrical design is also a concern.

The process of faceting can remove up to 60% of the raw stone. This is where the quality of the faciter comes into play. You don't want to lose too much of the raw stone, but you want the best cut you can get out of it.

While we might be tempted to create a formula to calculate the differences between the loss of material and type of cut to maximize the profitability of the raw stone, this didn't occur in the 14th century. A cutter cut what they knew how to cut. Some were well known for certain styles of cuts. Some were known to work with only certain types of gems. Mistakes were painfully expensive and the cutters could identify the work of another, highly renowned faciter.

The quality of the stone, as we already know, is based on the "color" and clarity. Here is an example of recent values of 3/4carat cut diamonds by color and clarity. Not immediately valuable for your D&D setting, but the relative differences between the x and y axis here is important to note.

According to my "sources" a 1 carat diamond (besides making for easy math) is "apparently" the line between tasteful and gaudy which is why the values in the chart linked to above are slightly out of whack with what one might expect.

I would probably start with that graph and then add another for the size of the diamond/gem, cut vs uncut, the quality of craftsmanship and the actual style of the cut.

Just a note, a 1 carat diamond weighs 200 mg. The size depends on the cut of course.

So there's some thoughts on gem value.

I haven't the time at the moment to get into distribution of gemstones in the 14th century. But perhaps someone else does?

Strixy said...

I forgot, storylines and gemstones.

While it would be cool to find a giant diamond in the bottom of a huge lair, another story could simply be finding an absolutely huge uncut diamond and the quest to find a faciter capable of cutting it correctly.

Either way, finding a buyer for such a rock is another quest entirely.

Alexis said...

In fact, and this shouldn't surprise you, I do have separate prices for raw, unpolished gems and for gemstones that have been cut into 'jewels' ... the latter being the designation I use for an cut stone. But you are spot on with your assessment of the situation.