Emerald

Emerald is one of the 8 Infusable gemstones. It can be Infused by burying it for 8 days, then let someone else retrieve it. Unearthing an emerald you buried yourself will immediately cancel the Infusion process. When Infused, they have a variety of uses:
 * Herblore: grants the drinker Nightvision.
 * Weapon: gains increased inertia, while the weight remains the same.
 * Shield: becomes completely weightless to the bearer.
 * Self-Infusion: grants Nightvision.
 * It is possible to create Twins.

On Twins
When two, and exactly two, Emeralds are: They will be tethered to one another. Such a pair of stones are called Twins. The two can be identified as Twins by the unique glowing rune that appears mirrored on the surface of the two gemstones. When one of the two paired gemstones are touched, it pulls the other gemstone towards it. The strength of the pull depends on the size of the gemstone. If one of the two gemstones lose their Infusion, both do, and will need to be Infused again. They can be Infused the regular way if they are already Twinned, and will remain Twins after it. If one of the two stones break, both turn opaque, and neither one of the Twins or their shards can ever be infused again. This form of uninfusable Emerald is known as Aventurine.
 * 1) Buried simultaneously by two different people,
 * 2) Remain in contact with each other during the 8 days needed for infusion,
 * 3) Are both simultaneously unearthed by the pair that buried it,