This is from a curse that I've seen on diamonds about their cuts.

The Hindus, who believed the virtue of every gem depended upon its perfection, considered a flawed Diamond so unlucky it could even deprive Indra of his highest heaven. The shape, too, was of great importance, especially in antiquity when few, if any, were cut. A triangular stone was said to cause quarrels, a square one inspired the wearer with vague terrors; a five-cornered stone had the worst effect of all, for it brought death. Only the six-cornered was productive of good.

Did you notice the bolded parts?

Triangular Cut- where have we seen that cut?

Quarrels were caused by her rebellion.

Square- a square shape is also a diamond shape. Where have we seen that?

These gems bring Vague Terror, makes sense. Vague terror is unclear why they're frightening or why they seem threatening. But they are scary. Very scary.

Five-Cornered-Where have we seen this?

Notice the pentagon(five-cornered shape) on her gem?

Five corner diamonds mean death. Didn't Rose theoretically "die," when she became Steven? (Fun Fact: Diamonds on the left side give victory over their enemies, in court and in war, if his cause is just. And Rose Quartz is left handed as shown with her pedestal in her armory she also won the battle for Earth.)

This helps the Rose Diamond Theory.

****Side Theory****
Look at the "Defective Diamond" part above. Defective has many meanings. Physically, Mentally, Emotionally. We know many people suffer from emotional trauma but we don't know who they are until they're on the floor balling with slit wrists. We don't know because they're the ones that look the happiest and laugh the most, like Rose. Defective could mean that Rose wasn't as emotionally stable as we think. What if she's defective because she, like humans, cut herself. Others believe her life is perfect but on the inside, it's not.

Take a pentagon and put an upside-down triangle on it. It should look like this,

(I recommend drawing if you can not see it in the visual representation.)

This means that the triangle, like on Rose's flag, and the Pentagon, like Rose's gem, make a Diamond. Meaning that Rose more than likely cut her gem in two and when her part of the gem meets the half she cut from herself, Pink Diamond will reemerge.