Like this?
player.getEntityAttribute(SharedMonsterAttributes.ATTACK_DAMAGE).applyModifier(redTearstoneRingBuff);
AttributeModifier redTearstoneRingBuff = new AttributeModifier(UUID.fromString("e6107045-134f-4c54-a645-75c3ae5c7a27"), "redTearstoneRingBuff", 0.5, 1);