Gems are typically several millennia old, though they may be only a few hundred years old when they explore the world.

Your base walking speed is 30 ft

Though you are a construct, you are a living creature. You are is immune to poison, diseases, and the effects of aging. You are do not need to eat, breathe, or sleep, though you may choose to ingest food and drink if you wish.
The Gemstone. A Gem's gemstone functions as the core of the Gem's being and the focus for their magical traits. Your gemstone is large enough to fill an average humanoid’s palm and protrudes from one specific section of your body, such as your shoulder or forehead. It is of middling-to-high quality, comparable to gems worth between 50 and 100gp, but it cannot be used as a spell component. Which gemstone you have is determined by your subrace.
Gem Withdraw. When your Hit Points reach 0 and you fall unconscious, you Withdraw. Rather than falling limp to the ground, your body retreats into the gemstone, in which you do not drop all your items onto the ground, instead, you and your items are put into a bubble, around 5 feet in area, Which last until either you stabilize, or you fail your save's and die. The bubble will use your AC and if hit, counts normally to the death save as a fail. You still make death saves and can be healed back to consciousness as normal. However, medical kits do not affect you, and you may be stabilized with a Arcana check, or the spell mending, with a DC 10. You reform from your gemstone a few minutes after you stabilize so long as you have room to do so.
Antimagic Susceptibility. You are stunned while in the area of an antimagic field. If targeted by dispel magic, you must succeed on a Constitution saving throw against the caster’s spell save DC or be stunned for 1 minute.
Gem Glow. Your gemstone can produce a dim light to illuminate dark places. As an action, your gemstone can shine a bright light in a 20-foot radius and dim light for another 20 feet.
Gem Weapon. All gems have a Gem Weapon stored within their gemstone that may be summoned in the same way that other races may draw regular weapons. A gem may choose any suitable common nonmagical weapon to be their starting Gem Weapon. The Gem Weapon can be replaced by any other suitable weapon during a Long Rest. When this is done, the Gem Weapon being replaced is destroyed and cannot be recovered. The new gem weapon will keep any properties it may have. Gem weapons that require attunement are automatically attuned to their owner and take up an attunement slot. All gem weapons count as magical for the purposes of overcoming resistance and immunity to nonmagical damage. Ranged Gem weapons do not require ammunition to fire, and gem weapons that are no longer being held by their owner, such as ones that have been dropped or thrown, will disappear at the end of each turn ready to be summoned again from their gemstone. You are considered proficient with your gem weapon.
Mutable Appearance. As Gems body and appearance are a manifestation of light, Gems can change their cosmetic appearance every time they are poofed should a gem go through this change they cannot change color, cannot change their size to the point where they become a different size category, and they cannot gain or lose any physical benefits from this change. The change is purely cosmetic.

You understand and can speak Common and Terran

You can choose Sapphire, Quartz, Ruby, Peridot, Lapis Lazuli, Pearl, Bismuth, Pearl, Aquamarine, Zircon or Spinel  as your subrace.