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. Tennis Ball

  22. A shoe belonging to a medium-to-large ventriloquist's dummy

  23. Half a paperback book (but only a short one)

  24. Potato (you know the sort of potato)

  25. Rock cake (which is a cake the size of a rock. A bit recursive, if you ask me)

  26. Half a tennis ball

  27. Half a tub of chewing gum, chewed up

  28. A squash ball with a ping-pong ball squeezed onto the end

  29. Penis (dog)

  30. Red Nose Day nose (for a human, not a car)

  31. Duck egg

  32. Chicken egg (and Cadbury's Creme equivalent)

  33. A testicle of an old man

  34. Coin

  35. Fingernail

  36. 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.