How large is a stone? Luckily, there is an internationally-agreed set of Standard Stone Units (SSUs)

Presented in descending order of size

  1. Baby (this is the assumed size of Richard's "Great White Stone")
  2. Football (size 5)
  3. A good portion of a breeze-block
  4. Wolfie's head
  5. Toy Millennium Falcon
  6. Flattened melon
  7. A house brick
  8. Hermione Hand (coincidentally, also the size of Richard's hand)
  9. A football that has been truncated about a third of the way up
  10. A Halloween mask that a child might wear
  11. A big rat
  12. Red Nose Day nose (car)
  13. Penis (human)*
  14. A third of a house-brick (NB. a entire house brick did not become an SSU until chapter 39)
  15. A partially-deflated child's football ( the ball is partially deflated, not the child)
  16. A small ball (bigger than a tennis ball, smaller than a football. Not the size you're imagining)
  17. Small dinosaur egg
  18. Small Easter egg (the type that would be disappointing if it was your main egg)
  19. Unripe pear
  20. Apple
  21. A shoe belonging to a medium-to-large ventriloquist's dummy
  22. Half a paperback book (but only a short one)
  23. Potato (you know the sort of potato)
  24. Rock cake (which is a cake the size of a rock. A bit recursive, if you ask me)
  25. Half a tennis ball
  26. Half a tub of chewing gum, chewed up
  27. A squash ball with a ping-pong ball squeezed onto the end
  28. Penis (dog)
  29. Red Nose Day nose (for a human, not a car)
  30. Duck egg
  31. Chicken egg (and Cadbury's Creme equivalent)
  32. A testicle of an old man
  33. Coin
  34. Fingernail
  35. Slightly larger than a grain of sand.

*Size can vary, which limits usefulness as a measuring device.

All these sizes of stones MUST be cleared.

The three-parameter scale

In Chapter 24, Richard proposed the three-parameter scale for stone sizing, which is designed to remove some of the confusion of the traditional SSUs.

After all, how are you supposed to know the size of an egg? It's virtually impossible to imagine an egg in your hand unless you actually have an egg there. But with the new system, the exact size of each stone can be accurately communicated. Richard toyed with the idea of a fourth parameter for "age of stone", but abandoned this as it would be impossible to determine without access to specialist geological tools.

Here are the agreed sizes, from largest to smallest:

large large large
medium large large
small large large
large medium large
medium medium large
small medium large
large small large
medium small large
small small large
large large medium
medium large medium
small large medium
large medium medium
medium medium medium
small medium medium
large small medium
medium small medium
small small medium
large large small
medium large small
small large small
large medium small
medium medium small
small medium small
large small small
medium small small
small small small

For clarification (not that it needs it, because it's bloody obvious), the three sizes do not refer to length, height and width of the stone.

If that was the case, a "medium medium small" stone would be the same size as a "small medium medium" stone. Whereas in reality the former is much smaller than the latter.

I mean, come on. This is basic stuff.