After long experimentations i would say:
Best grapples: ruby and sapphire (titanium grapples for price vs quality)
P.S i favorise range on grapples.
Best slingbow: diamonds (used as a shotgun from point blank), ruby (very long range bonus damage in nasharil), topaz (rapid fire and bonus damage on munteen)
Best tools: emerald(low damage but breaks five blocks at once, perfect for strip mining or gathering tons of ressources), diamond(med damage breaks three blocks), amathyst(good damage breaks two blocks) sapphire (one block heavy damage)
Thats my thoughts about gems stuff. Remember to have your four masteries required