I've never had more than one!-SapphireSapphire is a future-seeing gem who is currently fused with Ruby into Garnet.
borrowed from steven-universe.wikia.com
Sapphire is very compassionate, level-headed and patient. She balances out Ruby's much more impulsive personality when they are fused as Garnet. She is quick thinking; able to come up with quick solutions, as she came to the conclusion of Steven's immunity to the energy field almost immediately. This trait is also shown in "Gem Heist" when Sapphire is able to come up with a plan on the spot to enter Pink Diamond's Zoo undetected.
Because of her precognitive abilities, she comes off as cold and distant, due to having experienced the resolution of an event prior to it happening. This is shown in "Keystone Motel", where in which she feels the best option is to face problems by acting as though they have already been resolved. Because of this, she has trouble expressing her emotions in the present. This contrasts heavily with her partner Ruby, who has a difficult time concealing her emotions. Sapphire's blasé attitude to the present can make her appear somewhat passive-aggressive, but between Ruby and herself, she is also shown to be more outgoing, willing to start a conversation with one of her Ruby escorts about her thoughts on the Earth (shown in "The Answer"). When under a lot of stress, she is seemingly unable to control her powers, leading to her both figuratively and literally freezing up as ice begins to encase her, shown in "The Answer" and "That Will Be All".
In "Hit the Diamond", she is shown to have a more violent side to her. When the leader of the Homeworld Rubies threw a flaming fast ball, she managed to hit a homerun by encasing the bat in ice, all the while screaming with determination. In the same episode she's shown to be rather flirty with Ruby, to the point of detriment to her team.
Cryokinesis-Sapphire has cryokinesis, the control of ice.
Future vision-Sapphire has the ability to see the most likely outcome of the future.
Ruby-Sapphire is in a permafusion with Ruby and they are deeply in love, although they argue at times.
Pearl-Sapphire has not interacted with Pearl on-screen, but she is willing to forgive her quicker than Ruby.
Amethyst-Sapphire has not interacted with Amethyst on-screen, but they have very different personalities.
Steven-Sapphire would appear to have a caring relationship with Steven, although she does not understand his emotions at times.
Peridot-Sapphire has not been shown interacting with Peridot on-screen.
Lapis Lazuli-In the series "Gem-to-Gem", Sapphire and Lapis create meep morps together and discuss adjusting to the freedom Earth allows.
When fused with Ruby, they form Garnet.
When fused with Pearl, they form Moonstone.
When fused with Lapis Lazuli, they form Tanzanite.
When fused with Peridot, they form Dioprase.
When fused with Pearl and Ruby, they form Sardonyx.
When fused with Amethyst and Ruby, they form Sugilite.
When fused with Ruby and Peridot, they form Watermelon Tourmaline.
When fused with Ruby and Steven, they form Cherry Quartz 2.0.
When fused with Ruby and Rose Quartz, they form Cherry Quartz.
When fused with Pearl, Amethyst, and Ruby, they form Alexandrite.
When fused with Pearl, Ruby, and Peridot, they form Snowflake Obsidian.