Gems are a fairly-common and highly-prized type of Terrain Special - specifically one of the Minerals. This mineral appears as a bright diamond on the overland map, and is found only on Desert tiles by default. It is somewhat more common on Arcanus than on Myrror.
The presence of a single tile of Gems within the catchment area of a Town will raise that town's Gold output by exactly +5. This can be further boosted by the presence of the Marketplace, Bank, and/or Miners' Guild in this town.
Gems can be changed into Coal using the Transmute spell, and Coal can be changed into Gems using the same method. Gems can be removed from a tile by raising a Volcano in that tile. Corruption temporarily removes the bonus that Gems give to nearby towns.
Despite its attractive nature, Gold is not the most valuable of minerals. Strange crystalline formations, created from condensed chemical elements enduring millions of years of pressure underneath the earth, are even more coveted. These are the Gems, also known as "precious stones", and the most valuable of these are called "diamonds".
Most Gems are shiny and at least partially transparent, and they come in many shapes and colors. Their primary advantage over Gold is that they are extremely small for their relative value: a bag of Gems is significantly more valuable than a similar bag of gold coins. As a result, they can be used as a form of currency - when not used for aesthetic purposes of course.
In the game, Gems are represented by a single white diamond (though they are still called "Gems", not "Diamonds", in the game and on this wiki). They are very easy to spot on either plane.
Initial Placement and Terrain Edit
Gems are fairly common Terrain Specials, found in surprisingly high quantities on both Planes. However, the placement of Gems on the game world (done when a new game is begun) is based on random factors - so there is no real guarantee that any Gems will appear at all.
Gems will always be found on Desert tiles by default. It is possible, after the use of Terrain-altering spells like Change Terrain, to end up with Gems on Grassland or Forest tiles - but this does not happen without the use of such spells.
The only way to remove Gems is to raise a new Volcano underneath them. This permanently removes Gems from the affected tile - and they cannot be restored. Volcanoes can be created using either the Raise Volcano or Armageddon spells.
Mineral Effects Edit
Gold Bonus Edit
The presence of a Gems tile within the catchment area of a town increases the town's Gold output by exactly +5. In other words, the town will now produce 5 Gold every turn on top of what is produced from the town's citizens and other sources.
However, as explained below, several Town Buildings can capitalize on the availability of Gems to increase trade and make more money off it.
Town Building Bonuses Edit
There are two types of Town Buildings which can affect the Gold output of the Gems mineral.
First, the Miners' Guild building increases the base gold production of Gems by 50%, to 7. Secondly, any Gold bonuses, including the Marketplace, Bank, Merchants' Guild, as well as Road/River/Ocean Gold and Prosperity, will also multiply the bonuses from Gems. A patch of gems near a city with all of those effects and a population of 25 would produce 33.
It is possible to build two towns close enough together that their catchment areas overlap. Shared tiles are marked by a red "1/2" label, seen in each town's details screen.
Note that it is quite possible for this state to change during play, as new towns are established and existing towns are destroyed. The Gems tile's bonuses will be redistributed automatically in such events.
While this reduces Gold output, it can significantly boost the construction speed of new Normal Units in a nearby town. This is useful when your empire's Gold reserves are abundant, but you need to rapidly create new Normal Units. Note that, depending on the situation, it may just be better to spend the reserve gold on buying new units - but it's really up to you.
Remember that transmutation is not permanent: you can always cast the spell a second time to change Coal back into Gems.
The Corruption spell can be cast on a tile containing Gems. In such an event, both the Gems themselves as well as the tile they're on will cease providing any bonuses to nearby towns.
To combat this, send Shamans or Priests to Purify the affected tile immediately. If several tiles are Corrupted, Gems tiles are usually high on the priority list for Purification. Several spells, including Gaia's Blessing and Consecration, may also help if they are available.