You might want to choose a type of Gem that hasn't appeared in the show, since with them, your creative freedom is limited; Gems of the same type are virtually identical in appearance, and they typically serve the same purpose under the Order of the Diamonds. (If your Gemsona is a Crystal Gem, then you'll have more creative freedom.) Gems already shown, mentioned, or depicted in-series are:


Alexandrite
Amethyst
Aquamarine
Bismuth
Blue Diamond
Carnelian
Crazy Lace Agate
Fluorite
Garnet
Holly Blue Agate
Jasper
Lapis Lazuli
Malachite
Opal
Padparadscha Sapphire
Pearl
Peridot
Pink Diamond
Rainbow Quartz;
,, Gems tend to have interesting, even cool, clothes, but they're not terribly elaborate. Have a fair level of practicality in mind, especially if your Gem is a soldier or warrior. An aristocratic Gem might wear something more elegant.


Gems typically have their physical gems located in a place that subtly signifies something about them. Pearl's gem is on her forehead, reflecting on her logic and intelligence. Garnet's gems are on her hands, showing her inclination toward action and that she can be rash. Lapis Lazuli's gem is located on her back, showing that she is looking "back" at her Homeworld and wants to go "back" there.
A Gem's clothing also reflects upon their personality. Garnet wears a plain full-body jumpsuit, showing that she's straightforward and to-the-point. Amethyst wears casual looking clothes, showing that she's not so serious about things. Rose Quartz's long white dress resembles a wedding dress, pointing to her maternal qualities as well as her beauty.
Is your Gemsona a fusion? If so, how stable is she? What Gems have fused to make her, and what are they like?
How tall is your Gemsona? Is she child-sized, average human height, or nine feet tall? (If she's a fusion, she'll be even taller.)
If your Gemsona is a Crystal Gem, incorporate a star somewhere in her outfit. Every Crystal Gem has at least one star on her clothes.
 You can use any weapon, really, since the series shows everything from gauntlets to battle axes. Note, however, that no Gem shown yet has had a modern weapon, so avoid things like guns and grenades.


Some Gems have secondary abilities that can be used in combat (or not). Garnet has future vision, Pearl can project holograms from her gem, and Rose Quartz has healing tears. The series has also shown Gems with powers related to cold/ice and heat/fire, as well as electricity, water, and plant life.
 Gems, like humans, can be benevolent or callous, wise or reckless, friendly or cold. Some important things to consider include her attitude toward humans and the Earth, as well as whether or not she partakes in human activities, like sleeping and eating. Note that each Crystal Gem has been shown or implied to have some element of pain in her past. If your Gemsona is one of the Crystal Gems, remember that she went through a war at one point and has faced any number of traumas in her thousands of years.
 Compare your Gemsona to the Gems shown in-series. Is there anything about her that contradicts what the show has revealed about Gems? For instance, it's unlikely that she'd be as friendly with humans as Rose Quartz; Rose Quartz's love of humans has not been seen in any other Gem. If she's a Pearl, she must have been a servant or intended servant at some point. Try to make your Gemsona mesh well into the world of Steven Universe.
Pick a gem, any gem.
Rhodonite

Rose Quartz
Ruby
Rutile
Sapphire
Sardonyx
Smoky Quartz
Sugilite
Topaz
White Diamond
Yellow Diamond
Zircon

,
Design your Gemsona.
Choose your Gemsona's weapon.
Build her personality.
Fine-tune the details.
{"src": "wikihow-all_validation", "title": "How to Create a Gemsona"}