Kylo Ren:

His birthstone: citrine, his promise ring for you has a ruby (as you're born In the month of July)

Luke Skywalker:
his birthstone: sapphire, he's got you a promise ring bearing the stone of pearl. (Born on the month of June)

General Hux:
His birthstone: emerald. His promise ring to you bears the sapphire (born on the month of September.)

Poe Dameron:

His birthstone: aquamarine.
Your promise ring from him bears the zircon (you were born in the month of December.)

Han Solo:

His birthstone: ruby
His promise ring to you bears the amethyst. (Your birthday is in February.)

Finn:

His birthstone: aquamarine
His promise ring to you bears the peridot (you're born in the month of August.)

Obi-Wan Kenobi:

His birthstone: Aquamarine
His promise ring to you bears the garnet (you're born in the month of January.)

Anakin Skywalker:

His birthstone: diamond
His promise ring to you bears the citrine (you're born in November.)

Dedicated to Multifandom_99