Gems of Kaelaross

Base 10gp

Roll 1d8	Name	Source	Colour	Clarity
1	Banded Agate	Real	Red, White & Black	Opaque
2	Blue Quartz	Real	Pale Blue	Translucent
3	Malachite	Real	Different greens	Opaque
4	Mauvite	Mine	Different purples	Opaque
5	Nerisine	Mine	Bright Blue	Opaque
6	Obsidian	Real	Shiny Black	Opaque
7	Turquoise	Real	Bright Blue-Green	Opaque
8	Tiger Eye	Real	Gold & black	Opaque

Base 30gp

Roll 1d8	Name	Source	Colour	Clarity
1	Bloodstone	Real	Dark Grey & Red	Opaque
2	Carnelian	Real	Red-Brown & Black	Translucent
3	Citrine	Real	Yellow	Transparent
4	Clear Quartz	Real	Colourless	Transparent
5	Dioptase	Real	Blue-Green	Opaque
6	Lapis Lazuli	Real	Deep Blue	Opaque
7	Rhodochrosite	Real	Pale Pink	Translucent
8	Zircon	Real	blue or other	Transparent

Base 100gp

Roll 1d8	Name	Source	Colour	Clarity
1	Amber	Real	Golden Yellow	Transparent
2	Amethyst	Real	Purple	Transparent
3	Chrysoberyl	Real	Yellowish green	Transparent
4	Coral	Real	Bright Red	Opaque
5	Darkeye	Mine	Red with black center	Translucent
6	Jade	Real	Green	Translucent
7	Pearl	Real	White	Opaque
8	Tourmaline	Real	Green, Red or other	Transparent

Base 300gp

Roll 1d8	Name	Source	Colour	Clarity
1	Alexandrite	Real	Blue, Red or Purple	Transparent
2	Aquamarine	Real	Pale Blue	Transparent
3	Garnet	Real	Deep Red	Transparent
4	Magma Stone	Mine	Yellow and orange	Translucent
5	Peridot	Real	Light Green	Transparent
6	Spinel	Real	Red-Pink	Transparent
7	Topaz	Real	Golden Yellow	Transparent
8	Ultramarine	Mine	Deep Blue	Translucent

Base 1000gp

Roll 1d8	Name	Source	Colour	Clarity
1	Adamantite	Mine	Pale Green	Transparent
2	Black Pearl	Real	Black	Opaque
3	Emerald	Real	Bright Green	Transparent
4	Fire Opal	Real	Orange & gold	Translucent
5	Kraken-Eye	Mine	Deep Blue & Purple	Transparent
6	Opal	Real	Cyan and gold	Translucent
7	Ruby	Real	Bright Red	Transparent
8	Sapphire	Real	Bright Blue	Transparent

Base 3000gp

Roll 1d8	Name	Source	Colour	Clarity
1	Canary Diamond	Real	Bright yellow	Transparent
2	Dragonheart	Mine	Red & Purple	Transparent
3	Jacinth	Real	Orange	Transparent
4	Magestone	Mine	Magenta	Transparent
5	Star Emerald	Real	Bright Green	Transparent
6	Star Sapphire	Real	Bright Blue	Transparent
7	Star Ruby	Real	Bright Red	Transparent
8	White Diamond	Real	Colourless	Transparent

I have adapted the list of gems from 1E AD&D DMG and have been using this table or a variant of it for a while in both B/X D&D and other editions. This is not a definitive list, but a good random selection to start with - I could add more gems (either obscure real ones or fantasy ones) but I decided to keep it relatively simple. The values indicated can be varied as much as the DM wants, usually by changing either the quality or the size of the stone, so for example

Roll 1d8	Description	Value Multiplier
1	Damaged	x0.1
2	Very Poor	x0.2
3-4	Flawed	x0.5
5-6	Normal	x1
7	Flawless	x2
8	Perfect	x5

Roll 1d8	Description	Value Multiplier
1	Tiny (lentil size)	x0.2
2-3	Small (pea size)	x0.5
4-5	Normal (hazelnut size)	x1
6-7	Large (plum size)	x2
8	Huge (apple size)	x5

Thus a damaged, tiny obsidian gem might only be worth 2sp, while a perfect, huge star ruby could be worth 75,000gp