For a comprehensive list of other examples of issues with item positions in the Creative inventory, click here.

All tickets associated with item placement in the Creative inventory are valid for cases introduced in 1.16 and later as per this comment. Exceptions exist, which are valid for their own reasons.

The bug

Amethyst shards are not grouped with any of the items one may expect them to be grouped with. They are not grouped with diamonds or emeralds, despite amethysts, diamonds and emeralds all traditionally being precious stones, nor are they grouped with nether quartz, despite amethyst being a variety of quartz.

The recommend fix for this would be moving all four items next to each other.

How to reproduce

1. Open the Creative inventory
2. Locate Amethyst Shard in Miscellaneous
3. Locate Nether Quartz in Miscellaneous
4. Locate Diamond in Miscellaneous
5. Locate Emerald in Miscellaneous
6. Note that there is a considerable distance between these items