How do you get more shards and stones?

There's shards hidden underwater-use your Itemfinder and look for spots in the ground, usually there's somethng there-also get Heart Scales, too.

I'm sure there's at least one of each color. There's a million lists of where each of the stones can be found around Hoenn, BUT if you've gotten all of these(I'm guessing you did), all hope is not lost! First, if you have FR/LG or know someone who does, remember that all stones except sun/moon can be bought at Celedon Dept Store and given to a poke to hold for a trade over to your game. If not, you'll have to get a Pokemon with Thief(Mightyena&others) or Trick(Alakazam&others) or teach the TM for thief to someone.

Then go into the water-put a poke w/compound eyes in 1st place(they attract pokes holding items more frequently!)and look for Clamperls holding Blue Shards;Relicanth holding Green Shards;Corsola holding Red Shards, and Wild Chinchou holding Yellow Shards.

(Luvdisc hold heart scales sometimes, too.) You can either try to steal it from them in battle-it'll work but they aren't all holding shards, so it may take some time to get one. Or catch a bunch, see if any have shards, if not reset and try again.

Also, sun stones can be gotten the same way from Sunspike in Meteor Falls, but no Lunatones in Emerald so no moon stones to steal!
Well, hope that helps your desperation!

Well, you can only get 2 shards in this game (that I know of...) so the only way to get more of them is by doing cheats. Same thing with stones, except you get only one of each. Rate this answer.

Sorry, what I said before is wrong. Cross that out. You can find:
Blue Shard- use thief on wild Clamperl.
Water Stone- exchange for blue shard.
Green Shard- use thief on wild Relicanth.
Leaf Stone- exchange for green shard.
Red Shard- use thief on wild Corsola.
Fire Stone- exchange for red shard.
Yellow Shard- use thief on wild Chinchou.
Thunderstone- exchange for yellow shard.
Sun Stone- use thief on wild Solrock.
Moon Stone- use thief on wild Lunatone (in Sapphire).
Rate THIS answer, not my other answer.

Find dark spots in the ocean and use dive, then there are dark spots on the underwaterground, press them and you will get an item.(usually a shard)

All I can tell you about the shards is to dive anywhere between lillycove and mossdeep.But,for the stones I know you can get a fire stone in magma`s hideout, a water stone on the abandoned ship,a leaf stone near the weather institute (cross the bridge,go down and surf as south as possible.

There will be an item ball with the stone),and a thunder stone by the generator in the power plant (and also of course trading all the shards for different stones).

There is a moon stone found after you trade the meteor to the scientist in fallabor,also i hear all the time there is a hidden one in meteor falls, I haven`t looked yet, but feel free too look yourself.

Hope I helped, Evil.

Try looking on hidden islands