Sapphire

Ironman verdict

5 monsters drop it. The easiest is Goblin statue (level 70, 50/602); the best rate is Onyx dragon (level 126), at 11/128, about 1 per kill. You can also make it yourself: it takes 20 Crafting and gives 50 Crafting XP, using Uncut sapphire. Other sources include Baby impling, Baby impling jar, Thalassus and Dung kalphite, plus 3 more listed below. Making ten takes 10 × Uncut sapphire and gives 500 Crafting XP. Reaching level 20 Crafting takes 4,470 XP in total; the Crafting calculator counts the actions and materials to any target, and the Crafting guide has the Ironman training route. 17 recipes use Sapphire, including Ascended sapphire (unimbued), Blurite keystone and Deathwarden nexus (unattuned). Sapphire is available on free-to-play worlds too. It is tradeable on normal accounts, but an Ironman cannot use the Grand Exchange or trade for it, so the sources on this page are the whole list. High Alchemy turns one into 150 coins, which is 100 less than the shop price, so buying it to alch does not pay.