Scrap Materials, Enchanted Dust, and Glowing Shards can be obtained by salvaging certain items at the Blacksmith depending on the rarity. These crafting materials are used to upgrade your Gear, increasing your combat ratings.
Legendary Gems are used to craft enhancements for your equipment. It’s important to know as well that, Legendary Gems can be used to craft and further enhance other Legendary Gems.
Fading Embers are crafting materials used to buy Legendary Gems from the Fading Ember Merchant, giving you a chance to stack up on Legendary Gems and use those to craft and enhance your main Legendary gems.
Runes are another crafting material in Diablo Immortal, that can be used to craft Legendary Gems. Runes can be obtained from the Elder Rift event and also from the Fading Ember Merchant using Fading Ember.
Reforge stones are used to re-roll the certain attributes that your equipment has. With the use of Reforge Stones crafting material, you can get bonus attributes if your Reforge stones fall under the same Family.
Alchemical Powders are used to enhance or add skills to your Charm. You can obtain Alchemical Powder crafting materials by salvaging other charms.
Scoria can be obtained by doing your daily activities because it comes as a reward. Scoria is used to enhance your Helliquary levels, giving you a chance to fight other Helliquary bosses. But as of now, Hellfire Scoria is the only one available.