Most of the currencies in the game can be used to make AD, although some are better than others.
Gold.Gold can be made into Astral Diamonds by buying Gold Bars from a Vendor and selling them on the Auction House.
Guild Marks -Explorer’s Chart Farming:
For most Neverwinter players, Masterwork Professions (see further down), is just too much work and too expensive. But you can still make a profit from farming and selling the resources needed by the Masterwork recipes. The profitability of this varies a lot as the prices of the different resources change. As of mod 14, the prices are down, at least on PC, so waiting for further updates might be best.
Before you start farming, check which resources fetch high prices and farm accordingly.
To really take advantage of Explorer’s Chart farming, you should also use events to your advantage. Donate to your guild during 2x Guild Mark events, and save up the Explorer’s Charts for the 2x Profession resources events. After a 2x Profession event, wait a while before selling the resources, as the prices will likely drop during the event.
After you have refined all of your own gear, you can start using your leftover RP to refine enchantments that you can sell on the AH. You don’t have to refine enchantments very high up to make a profit, and just buying rank 5’s and refining to rank 7 or 8 can be profitable, as long as you farm all your own RP and don’t have to buy it.
Some enchantments are more profitable than others, and the normal ones like Azures, Darks, etc, are the least profitable. Black Ice and Brutals tend to be pretty good choices, but prices vary so check the Auction House to find out which enchantments sell for the most.
Having a spreadsheet with all the costs can also be very useful to figure out how much you are making per enchantment. Simply write down how much you are spending on refining enchantments from rank to rank, and compare with how much you can sell it for.
You get Celestial coins the first time you invoke each day on each character. Once you have 11 Celestial coins, you can spend them on coffers that can reward a Coalescent Ward. RNG is a big factor here so you won’t be getting these a lot, but the more characters you have, the better your chances are, so remember to invoke at least once on all your characters. To make money from these Coalescent Wards, you will want to Armor or Weapon Enchantment shards. These only cost a few hundred. Find out what enchantment currently sells for the most, buy a shard, then use your Coalescent ward to upgrade it, and profit.
Seal of the Brave: Quickly stacks up from doing dungeons and events.
Gold: Make into AD by buying from vendors and selling on AH. Injury Kits, Mounts and Companions work best.
Seal of the Adventurer: Can be traded for rough AD.
Tarmalune Trade Bars: Use during discount events to buy Mounts or Companions to sell.
Demonic Ichor: Use to buy Drowcraft shirt and pants that can be sold on the AH.
Most of the campaigns have some sort of currency that you can NeverWinter Astra Diamonds with but its generally not worth farming these.