Apparel Augment Gems

An apparel augment gem is a small gem, crystal, or similar object that provides a magical effect when affixed to a piece of clothing, armor or a shield. Each item can hold a single augment crystal, but an attached crystal can be swapped for another one at any time. Attaching an augment crystal to (or removing it from) an item requires a move action that doesn’t provoke attacks of opportunity. Effectively, each eligible item has a single “slot” that can be filled by any appropriate augment crystal.

Crystals can come in 3 forms, Lesser, Moderate and Greater. You must meet the level of a crystal to be able to use it.
Lesser Gems – 3rd Level
Moderate Gems – 9th Level
Greater Gems – 15th Level
You get the effect listed for your rarity of gem plus the effects for the lower rarity gems. (ie. a greater gem gets the moderate and lesser effect) HOWEVER bonuses of the same kind do not stack, so you cannot wear two gems of warding to get a higher DR, but you can wear two gems of elemental defense provided they are for different elements.

NOTE – 2 indentical gems can be fused to create a gem of the rarity up. (ie two lessers make a moderate.)

Gem of Aptitude

A gem of aptitude enhances your skill at certain tasks, each gem is aligned to two skills.
The pairings are:
Nimble = Athletics + acrobatics,
Sneaky = Sleight of hand + stealth,
Silver Tongue = Persuasion + deception,
Showboat = Performance + intimidate,
Survivalist = Nature + survival,
Caring = Animal handling + medicine,
Inquisitive = Investigation + arcana,
Knowledgable = History + religion,
Hawkeye = Insight + perception.
Lesser – You gain +1 to the paired skills.
Moderate – You gain +2 to the paired skills.
Greater – You gain +3 to the paired skills

Gem of Elemental Defense

A gem of elemental defense is attuned to an elemental plane. It protects the bearer from the associated energy type. They grant benefits depending on the colour of the gem (red-fire, blue-cold, green-acid, yellow-lightning, black-necrotic, white-radiant).
Lesser – You gain DR/3 against the associated element, you are also immune to environmental conditions associated with the element (ie. extreme heat – fire).
Moderate – You instead gain DR/5 against to the associated element
Greater – You gain Resistance to the associated element.

Gem of Magnetism

A gem of magnetism causes your armor to pull at or push away foes
Lesser – You gain a +2 to any grapple check.
Moderate – You instead gain a +5 to any grapple check.
Greater – You instead gain a +10 to any grapple check.

Gem of Movement

A gem of movement makes getting around a breeze.
Lesser – Gives it wearer a swim speed and a climb speed equal to one-half your land speed (round down to the next 5-foot increment).
Moderate – You can breathe water as easily as air, and take quarter damage from falls.
Greater – You gain a fly speed equal to half your movement speed, and your swim and climb speed increase to match your movement speed.

Gem of Resilience

A gem of resilence protects you from assaults against your physical and mental health. Each gem is attuned to 1 physical and 1 mental stat. (str+cha, dex+int or con+wis)
Lesser – You gain +1 to the associated saving throws.
Moderate – You instead gain +2 on the associated saving throws.
Greater – You also gain advantage on the associated saving throws.

Gem of Rune Magic

This gem has a rune etched into its core, the runes embody certain magical tattoo’s. The power level of the tattoo depends on the rune gem level.
Lesser – A Small Simple rune.
Moderate – Instead it has either a Small Average rune, OR a Medium Simple rune.
Greater – Instead it has either a Small Intricate rune, OR a Medium Average rune, OR a Large Simple rune.

Gem of Warding

An iron ward diamond lends its toughness to armor, helping it absorb blows in combat.
Lesser – You gain a damage reduction of 1.
Moderate – You instead gain a damage reduction of 3.
Greater – You instead gain a damage reduction of 5.

Image – https://homebrewery.naturalcrit.com/print/ryXHUftFZ?dialog=true