Glyphscape/Gems

Jewelry Overview
Occasionally in RS3, you will find an uncut gemstone, such as by defeating enemies or via mining. Just about every gem in RS3 has magical properties, most of them carrying combat benefits. Gemstones can then be chiseled into cut gems, which vary in three criteria: color, cut, and carat:


 * Color is what type of gem it is, as in RS3, each type of gem corresponds to only one color. Different types of gems have, as you'd expect, different effects.
 * Cut is the shape a gem is cut into. Different cuts enable a gem to be used in different places/jewelry.
 * Carat is the size and thus grade of the gem. The smallest size a gem can have is 1 carat, and the scale increases by increments of 1 carat, with no set upper limit. The greater the size (measured in carats) the gem, the greater is its effect, and the greater its value and rarity.

There is no way to change the color or carat of a gem or gemstone. It is however possible though costly to change its cut.

The color of a gemstone is randomly selected, without much difference in their rarities.

On average players find one gem every 4 hours of active game time, and this does not improve notably with increases in leveling.

Gems can be placed into the sockets commonly found on equip-able items. They are the most expensive means of improving a character's (usually combat) stats. Gems can also be made into jewelry for various other beneficial effects. Once socketed, gems can only be retrieved by destroying the item the gem was socketed into. For owners of the most valuable gems, this is barely a problem - gems can be just that incredibly valuable.

Carat
Every doubling of a gem's carat (size) doubles its effectiveness (though some effects compound multiplicatively).

There is no set upper limit to how large a gem can get, so theoretically there can be a gem of 1,000,000+ carats, but in practice as you go up the size scale the rarity of such gems increases exponentially so it is just about impossible for any player in the history of the game to get their hands on a really, really large gem.

When you stumble across a gem, its carat is determined by the following randomization schedule:

All pre-gemstones start at 1 carat. The chance that a pre-gemstone gets promoted (carat +1) instead of being finalized by the game into a gemstone is (1/16) ^ (2 / (Current carat of pre-gemstone x 2 + 1)). If the pre-gemstone is promoted, then it is not finalized and the promotion cycle repeats. (Players never see the pre-gemstone.) Thus a 1-carat pre-gemstone has a 15.75% chance of being promoted to a 2-carat pre-gemstone, with double the effects, while a 2-carat pre-gemstone has a 32.99% * 45.29% (14.94%) chance of being promoted to a 4-carat pre-gemstone which once again doubles its effects. Each doubling of carat size (and hence effect) averages out at a 14.6% chance. It's not easy to place a rarity score for any particular carat, since single-carat promotions for larger pre-gemstones are more common but less effective. But its trade value is, as with many tradeable items, a good reflection of its worth.

Since each doubling of carat size corresponds to a roughly four-fold increase in value but six-fold increase in rarity, a player's expected earnings per unit of time don't go off to infinity, but rather, converge.

Table of Gem Sizes
Values listed are for the average color, uncut gemstones. Each successive gemstone features twice the carat as the one before.


 * Note: Gems larger than 500 carat are so rare they do not have reliable market values. For them, only estimates are provided.

Trivia
While most players get quite a few low-level gemstones before getting any skill to level 50, they may have found perhaps one 4-carat ("standard") gemstone by that time. Given enough time, a typical power-player with several near-level-100 skills has found a 16-carat gemstone and, if they focus on buying gemstones at the expense of all else, the best may have traded for a 64-carat gemstone. 10 years after RS3's launch, about a billion gemstones have been found, of which ~500,000 are of 16-carat or higher, and ~200 are of 256-carat or higher.

The 2nd largest through 5th largest gemstones of any type found in the first 10 years of RS3's history are a 920, 836, 799, and 784-carat, none of which could be traded at even close to their true value due to a lack of billionaire buyers. Of these, none are still being actively used (they were all stuck in inventories belonging to players who are no longer playing). The chance of any gem being of size 512-carat or greater is about 1 in 40 million.

Merely two weeks into the launching of RS3 (and when there were only a few people playing), an unique, exactly 3,600-carat diamond was found. Named "The Protector", it remains the single most valuable gem ever discovered in RS3's history, with a rarity of 1 in 7 billion. It is still active, having been traded right before their ex-owners stopped playing the game (as they knew just how precious it really was). Paradoxically, in its last 10 changes of ownership the average trade for it was a token 100,000 gp, with all exchanges being to give them to the owners' best friends in-game - about the same cost as a 16-carat. If not for this tendency, The Protector would be appraised at 2-4 billion gp! It remains a particularly salient subject of Runescape lore.

The Protector is generally used as a defensive gem. In such a capacity its stat boost when socketed is "+2% to all resists ^ 900" compounded, or as it shows up in-game, "99.9999+% to all resists compounded", making the bearer take 0 damage from all sources of damage no matter how powerful, even weapons enhanced with the other most valuable gems, hence its namesake. No other single gem affords true immunity to everything. By comparison, a standard (4-carat) diamond used in a similar way would have "+2% to all resists".