Disenchanting requires destroying a green quality item or better to get materials for enchanting abilities. This is invaluable when farming instances because of the number of BoP items you pick up that most likely will be of no use to you. This following chart shows what you may get from the quality of the item you disenchant.
Item Color & Disenchanted Items (Most Likely)
Green – Dust
Blue – A Shard
Purple – Essence, Shard(s), and/or Dust(s)
Orange – Likely multiple shards
Red – Unknown, items are rare and not yet DE’d
This next Data will be explaining what your enchanting skill needs to be before you can disenchant higher level equipment. The higher you enchanting skill goes you can DE higher level items, Enchanting was not always based like this but it was done to keep a balance within the trade skill so you actually had to invest in an enchanter to take advantage of its secondary skill.
Enchanting Skill – Item Level – Disenchanted Materials
Enchanting 1 – Level 1-15 Strange Dust, Lesser or Greater Magic Essence, and Small Glimmering Shard
Enchanting 25 – Level 16-20 – Strange Dust, Lesser Astral Essence, and Small Glimmering Shard
Enchanting 50 – Level 21-25 – Soul Dust, Greater Astral Essence, and Large Glimmering Shard
Enchanting 75 – Level 26-30 – Soul Dust, Lesser Mystic Essence, and Small Glowing Shard
Enchanting 100 – Level 31-35 – Vision Dust, Lesser or Greater Mystic Essence, and Large Glowing Shard
Enchanting 125 – Level 36-40 – Vision Dust, Lesser Nether Essence, and Small Radiant Shard
Enchanting 150 – Level 41-45 – Dream Dust, Greater Nether Essence, and Large Radiant Shard
Enchanting 175 – Level 46-50 – Dream Dust, Lesser Eternal Essence, and Small Brilliant Shard
Enchanting 200 – Level 51-55 – Illusion Dust, Greater Eternal Essence, and Large Brilliant Shard
Enchanting 225 – Level 56-60 – Illusion Dust, Greater Eternal Essence, Large Brilliant Shard, and Nexus Crystal
The above data only outlines the items that are possible to receive through disenchanting and these items are not guaranteed to drop off of disenchanted items, those Items can easy exchange to wow classic gold US at the auction house. but give you a great idea of what you might obtain. The reason for this is each item has a separate value for what will drop from it being disenchanted. Using the above 2 charts together should give you a great idea of what your disenchanted item may yield.