You will need "Star Gem Shard", which you can obtain by recycling avatars, to create Star Gems.
The number of Star Gem Shards you can get depends on the part of Avatar such as Top, Bottom and Accessory.
How to Get "Star Gem Shard"
Select "Break into Star Gem Shards" in the recycling menu.
Tap the avatar item to recycle into Star Gem Shards and tap "Recycle".
Tap "Recycle" to get the Star Gem Shards.
Create Star Gems!
You can create Star Gems from [Menu > Character > Skills > Star Gem > Create Star Gems].
If you select "Use 100 Shards", a Star Gem with a randomly selected Lv1 skill (except certain skills) will be created.
If you select "Use 1,000 Shards", you can select a skill tree and put a Lv1 skill (except certain skills) on the Star Gem.
Also, you can create a Star Gem with a randomly selected Lv1 skill for Orb x3 one time only per day.
Therefore, the creation process of the Star Gem created with Orb x3 is the same as the one created with 100 Shards.
Let's equip Star Gems after creation!
Tap [Menu > Star Gem] to create, enhance or equip Star Gems.
How to Equip Star Gems
To use the skills on Star Gems, you need to equip Star Gems from [Menu > Star Gem > + Equip Star Gems].
The limit of the cost for Star Gems depends on the highest level of your characters.
If you have a high level character, your new character can equip Star Gems with high costs.
Each Star Gem has a cost depending on the level of the skill tree.
As the level of the skill tree gets higher, the costs of the Star Gems get higher.
e.g.) Quick Draw (Shot Skill) is included in Lv3 Skill Tree, so the cost is "3".
Hard Hit (Blade Skill) is included in Lv1 Skill Tree, so the cost is "1".
Enhance Star Gems!
Star Gems with the same skill can be enhanced by synthesizing it. (The skill levels up.)
If you enhance them, the skill level of the consumed Star Gem will be added to the base Star Gem.
Please note that the max level for skills is 10.
Tap [Star Gem > Confirm Star Gems Owned > Enhance to enhance Star Gems].
Evolve Star Gems!
The Star Gem that reached Lv10 can be evolved to the next skill (the skill on the right side) on the skill tree.
The skill level of a evolved Star Gem will return to Lv1.
Tap [Star Gem > Confirm Star Gems Owned > Enhance (Shown only when you have a Star Gem with a Lv10 skill.)] to enhance Star Gems.
Break Unnecessary Star Gems!
You can break unnecessary Star Gems into Star Gem Shard x50 and Mana Points.
The amount of Mana Material Points get higher as the cost of the broken Star Gem gets higher.
Tap [Star Gem > Confirm Star Gems Owned > Break to break Star Gems].
*If you have learned the same skill with a Star Gem you equip, the skill with higher level will be available.
*"Star Gem" menu in "Skills" will be displayed by meeting the following conditions.
・Own a character with Lv40 or higher.
・ Own 1 or more "Star Gem" or "Star Gem Shard".
*The rarities of avatar items don't affect the number of Star Gem Shards obtained by recycling avatars.
*The number of times you can create Star Gems with Orb x3 will be reset at 5:00 AM (JST/GMT+9).
*The Star Gems equipped by another character cannot be enhanced.
*Star Gems with Lv10 skills cannot be enhanced.
*A skill on a Star Gem can be evolved to the next skill on the right side in the skill tree.
Please note that the skill cannot be evolved to the next skill on the left side.
*You cannot evolve a Star Gem to a skill that cannot be learned due to lack of level.
*Star Gems can be traded in future update.
However, Star Gem Shards cannot be traded.