Ivorymoon weapons are obtained when the player reaches the Silverfrost region, or when a sufficiently upgraded Hongmoon weapon previously obtained from the first chapter of the story or Viridian Valor Stone Trader.
Like the now-defunct Hongmoon weapons, Ivorymoon weapons are the first upgradeable equipment pieces that players are able to obtain. The progression of weapon growth is as follows, with each section broken up into Stages 1-5 and Stages 6-10, like most other upgradeable equipment pieces: Ivorymoon, Awakened Ivorymoon, and True Ivorymoon (colloquially, players often shorten those names into "ivory", "aivory", and "tivory", respectively). After reaching True Ivorymoon Stage 10, the player can upgrade his/her weapon to the first stage of one of the two legendary weapon types, namely Seraph and Baleful.
These are the costs of going through each stage.
Note to other editors - consider deletion/revamp of this page in favor of a so-called "Weapon Progression" page that will be listed under a future "Equipment Progression" category to be added to front page.
The rationale for such a proposal is that this page is currently listed under "Weapons" giving the entirely false impression that there is in fact a sufficiently great scale of lateral weapon progression in BnS to warrant such a classification system.
However, while this setup works very well with limited amounts of information, it admittedly will become clunky once vast piles of information are added. On the other hand, this will most likely not become a problem for the short term.
I agree there should be a weapon progression list, but not as a replacement for the weapons category. This category should also include weapons that players don't actually use such as Yeti or Scorpion. What I would recommend is a separate page that is for weapon progression. Then this page links to the specific weapon tier for full information. There should also be a page for acc progression as well. This way we still have a complete source of information for all of the gear without having a really large page. p.s. This discussion would be a great use of the forums. The talk page is ok too.