3rd Edition D&D Gems & Stones

Bladestone (Invented by Hogan)

A Bladestone is an almost oval stone, consisting of raw iron with small etchings of rust. All around the center is a small saw-toothed and sharp iron outcropping.
The stone can be used as a sling bullet, but due to its irregular features, the user receives an -2 penalty to attack, but it does a flat +2 points in damage due to the sharp edges of the stone. The stone's major power however, is much more deadly than this. When a command word is uttered, the stone will burst into a horizontal Blade Barrier, as per the 6th level divine prayer, covering an area 30 feet on each side where the room allows. This form cannot be altered, and if the room doesn't allow it to expand in one direction, it cannot extend in another instead, but is simply reduced in size.
The barrier remains in effect (unless dispelled) for 2 hours before it dissipates. Those caught in its initial invoking are entitled to a reflex saving throw at (DC 16) to avoid it completely (jump free). Those missing their reflex saving throw or tries to pass through the barrier while it is active take 13d6 in damage.
The Bladestone is a single use item.

Caster Level: 11th; Prerequisites: Craft Wondrous Items, Blade Barrier
Market Price: 3,300 gp; Creation Cost: 1,650 gp + 132 XP.

Component Stone (Invented by Hogan)

Component Stones are small ceramic baubles of about '' in diameter. A such can substitute almost any component M,F or DF for use in a spell or prayer, as long as it is not reusable and doesn't cost more than 100 gp in open bargain. Hence, the stone cannot substitute a 500 gp diamond, or the crystal rod for a Lightning Bolt spell.
In order to use the stone, it just has to be taken out during casting and handled exactly like the original component, then the substitution will take place, and the stone will dissolve afterwards.

Caster Level: 7th; Prerequisites: Craft Wondrous Items, Minor Creation
Market Price: 1,400 gp; Creation Cost: 700 gp + 56 XP.

Creature Gem (Invented by Martigan)

These magical gemstones are the legacy of the wicked magic of a long gone Drow Priest that combined his belief in Vhaeraun with a mage's magical powers. With twisted magic he bound monsters into precious gemstones, to be released at his will and to fight under his control.
A Creature Gem acts as a container for a Summon Monster spell, the more precious the gem, the more powerful the monster.
To release the monster, the gem has to be crushed. Due to the magic involved, all gems are a breakable as rock crystal. The gem has to make a Fortitude saving throw (DC 5) to survive. Once the gem is broken, the monster contained within is released in full size. To take control of the monster, the correct word of command (imbued in the gem at the magical imprisonment of the monster) must be uttered at the destruction of the gem.
When found, there will usually be 1d4 Creature Gems together, roll on the following table below to see what kind is at hand:

1d100 Gem Class As spell Caster Level Market Price Creation Costs
01-45 Ornamental (10) Summon Monster I 10th 60 gp 35 gp + 2 XP
46-65 Semi-Precious (50) Summon Monster II 10th 350 gp 200 gp + 12 XP
66-80 Fancy (100) Summon Monster III 10th 850 gp 475 gp + 30 XP
81-90 Precious (500) Summon Monster IV 10th 1900 gp 1200 gp + 56 XP
91-95 Gems (1000) Summon Monster V 10th 3250 gp 2125 gp + 90 XP
96-99 Jewels (5000) Summon Monster VI 11th 8300 g 6650 gp + 132 XP

Check the appropriate table in the Players Handbook and when determining what random monster is captured within. If more gems are found, all monsters will be at the same alignment. The summoned creatures have a duration of 10 rounds.

The Creature Gems will in any way be identical to normal gems, except that they radiate magic, which can be detected by a Detect Magic spell. Spells of revealing like True Seeing and similar will reveal what kind of creature is bound in the gem. An Identify spell will reveal the nature of a stone, and the necessary command word, but not the content of the gem.
Sometimes (25 % chance when found) the creator has by some means marked the gem so as to be able to quickly recognize the gem himself.

Caster Level: Varied; Prerequisites: Craft Wondrous Items, Summon Monster (I+VI)
Market Price: Varied; Creation Cost: Varied.

Danger Stone (Invented by Hogan)

A bluish marble, polished as smooth as possible, the Danger Stone is a beauty to behold, and many adventures see it as a token of luck. While the stone itself hasn't any luckgiving properties, it possesses another skill that is highly appreciated by its owner, the ability to detect danger!
If the stone is laid in the palm of a naked hand (no gloves, gauntlets or such) and struck out into a general direction, the stone will sense if there is danger for the user within a range of 30 yards, and in a 90 degree cone in the direction it is put. If there is danger present, the stone will glow red, the degree of redness showing the degree of danger ahead. There is no way to tell what kind of danger the stone detects. It could be ambushing Kobolds, sleeping Dragons, unsprung traps or wandering Wyverns, anything that could be a threat to the stone's owner. That nothing happens despite the indication of danger, is not a sign of malfunction, the danger was apparent at the time of detection, but the user either too another road, the monster moved on or such.
The stone can only be used once every day, or it will start giving out wrong indications. Danger where none is present, little danger where demons dwell or such.

Caster Level: 17th; Prerequisites: Craft Wondrous Items, Foresight
Market Price: 17,212 gp; Creation Cost: 8,606 gp + 688 XP.

Gem of Weather Control (Invented by Martigan and Hogan)

The Gem of Weather Control is a clear glassy gemstone, which translucent inner seems to be alive with hazy clouds, swirling among themselves. As the name predict, the holder of the gemstone is able to change the weather as per a Control Weather spell, for a duration of up to one day in an area of 12 square miles. When the duration runs out, the normal weather of the area wins back.
The stone is powered by 2d20 charges, measured in the amount of clouds within. As the charges are used, the clouds thins out until, finally, the last cloudy wisps disappears, and the Gem is a normal glass bauble once more. There are no set ways to recharge this item. Each change in weather conditions requires one charge, and each change takes 1d4 rounds to take effect. And infinite number of charges can be used cumulative, but the duration is set according to the first change in the weather. Unless other magic where uses to counter the effect, the weather will hold out for the whole 24 hours, staying in the area, before blowing out and returning to normal. Only by spending charges, the holder of the Gem of Weather Control can change his own magically altered weather conditions.

Caster Level: 13th; Prerequisites: Craft Wondrous Items, Control Weather
Market Price: 68,250 gp; Creation Cost: 34,125 gp + 2730 XP.

Stone of Stoning (Invented by Hogan)

A Stone of Stoning is a small oval piece of rock of about 1 inch. When inspected very closely, a person will be able to se small runes covering the whole stone.
The stone can be either thrown or launched with a sling or similar. When speeding towards it target, the stone will suddenly start multiplying, until the target is hit by a veritable rain of stones. It is almost impossible to avoid all the stones, and the number of hits can be determined by making a to hit roll with a +2 modifier.

Missing armor class by more than four points1d2 stones (none if making a Reflex save (DC 13)
Missing armor class by 1-4 points1d4 stones
Hitting right on armor class2d4 stones
Hitting an armor class 1-4 points lower than needed3d4 stones
Hitting an armor class 4 or more points lower than needed4d4 stones

The Stone of Stoning can only be used once, and when used then runes on it will disappear.

Caster Level: 3rd; Prerequisites: Craft Wondrous Items, Mirror Image, Magical Stone
Market Price: 350 gp; Creation Cost: 175 gp + 14 XP.

Wall-Builder (Invented by Hogan)

A rough-cut granite pebble, about 2 inches wide with a small silver band around the middle, this one is one of the more heavy magical stones around. When a command word is uttered and the stone dropped/thrown it will on the point of impact explode into a million magical sparks, immediately reshaping into a massive wall of stone.
This wall is similar to that created by the spell Wall of Stone. The wall created will be roughly three inches thick, 6 feet high and 15 feet wide. If created in a place (like in a tunnel) with less room than this, it will expand to its maximum allowed size.
The wall is created horizontally and stabile. It cannot be created to catch living creatures. Those in its way are pushed aside as it expands. Inanimate objects will become a part of the wall unless they are large (larger or wider than the wall itself) enough to act as a barrier to the wall's expansion.
Like with the spell, the wall is permanent unless dispelled.

Caster Level: 16th; Prerequisites: Craft Wondrous Items, Wall of Stone
Market Price: 2250 gp; Creation Cost: 1125 gp + 14 XP.