Open minecraft.jar and open the lang folder, then find the language you use and open it with a text editor. Then add this anywhere in the file on a new row:
item.pickaxeEmerald.name=Emerald Pickaxe
item.swordEmerald.name=Emerald Sword
item.shovelEmerald.name=Emerald Shovel
item.hatchetEmerald.name=Emerald Axe
item.hoeEmerald.name=Emerald Hoe
item.helmetEmerald.name=Emerald Helmet
item.chestplateEmerald.name=Emerald Chestplate
item.leggingsEmerald.name=Emerald Leggings
item.bootsEmerald.name=Emerald Boots
tile.oreRuby.name=Ruby Ore
tile.blockRuby.name=Block of Ruby
item.pickaxeRuby.name=Ruby Pickaxe
item.swordRuby.name=Ruby Sword
item.shovelRuby.name=Ruby Shovel
item.hatchetRuby.name=Ruby Axe
item.hoeRuby.name=Ruby Hoe
item.helmetRuby.name=Ruby Helmet
item.chestplateRuby.name=Ruby Chestplate
item.leggingsRuby.name=Ruby Leggings
item.bootsRuby.name=Ruby Boots
item.sapphire.name=Sapphire
tile.oreSapphire.name=Sapphire Ore
tile.blockSapphire.name=Block of Sapphire
item.pickaxeSapphire.name=Sapphire Pickaxe
item.swordSapphire.name=Sapphire Sword
item.shovelSapphire.name=Sapphire Shovel
item.hatchetSapphire.name=Sapphire Axe
item.hoeSapphire.name=Sapphire Hoe
item.helmetSapphire.name=Sapphire Helmet
item.chestplateSapphire.name=Sapphire Chestplate
item.leggingsSapphire.name=Sapphire Leggings
item.bootsSapphire.name=Sapphire Boots
item.amethyst.name=Amethyst
tile.oreAmethyst.name=Amethyst Ore
tile.blockAmethyst.name=Block of Amethyst
item.pickaxeAmethyst.name=Amethyst Pickaxe
item.swordAmethyst.name=Amethyst Sword
item.shovelAmethyst.name=Amethyst Shovel
item.hatchetAmethyst.name=Amethyst Axe
item.hoeAmethyst.name=Amethyst Hoe
item.helmetAmethyst.name=Amethyst Helmet
item.chestplateAmethyst.name=Amethyst Chestplate
item.leggingsAmethyst.name=Amethyst Leggings
item.bootsAmethyst.name=Amethyst Boots
item.topaz.name=Topaz
tile.oreTopaz.name=Topaz Ore
tile.blockTopaz.name=Block of Topaz
item.pickaxeTopaz.name=Topaz Pickaxe
item.swordTopaz.name=Topaz Sword
item.shovelTopaz.name=Topaz Shovel
item.hatchetTopaz.name=Topaz Axe
item.hoeTopaz.name=Topaz Hoe
item.helmetTopaz.name=Topaz Helmet
item.chestplateTopaz.name=Topaz Chestplate
item.leggingsTopaz.name=Topaz Leggings
item.bootsTopaz.name=Topaz Boots
