The temperature and pressure near the center of gas giants is crazy high. For Jupiter [0]:
> The temperature at the core boundary is estimated to be 36,000 K (35,700 °C; 64,300 °F) and the interior pressure is roughly 3,000–4,500 GPa.
It's similar to why you wouldn't be surprised to find diamonds deep underground in a mine, but if you found tiny diamonds forming in clouds that would be a major revelation.
> The temperature at the core boundary is estimated to be 36,000 K (35,700 °C; 64,300 °F) and the interior pressure is roughly 3,000–4,500 GPa.
It's similar to why you wouldn't be surprised to find diamonds deep underground in a mine, but if you found tiny diamonds forming in clouds that would be a major revelation.
[0]: https://en.wikipedia.org/wiki/Jupiter#Physical_characteristi...