Disclaimer: I'm not sure if this is the right place for this; if it's not, please move. Moreover, this guide contains info involving both the 3rd and 4th Generations, but it focuses on Platinum Move Tutors, hence I posted it in the DPPt section.
Pokémon RSE-FRLG & DPPt Shards Guide
By ViniMC
1-Introduction
Shards were introduced in the third Generation. They are most commonly found underwater in Hoenn, but can also be held by Wild Pokémon and dug up in the Sinnoh Underground. Their use prior to Platinum was limited to exchange for Evolutionary Stones (RSE) or for Weather TMs (DP); however, in Platinum, Shards can be given in groups of eight to three different Move Tutors, who teach a huge variety of moves. This feature was removed in HGSS (they cost BP now) – instead, Shards can be given to two Jugglers for Berries, one in Violet City and another one in Fuchsia City.
The following list shows all uses for Shards in every 3rd and 4th Generation game. Thanks to Bulbapedia for those lists:
Red Shard
Can be traded for a
Fire Stone.
RSE
Can be traded for
TM11 (
Sunny Day).
DP
Can be traded for a
Cheri,
Leppa, and
Pecha Berry (
Violet) or a
Persim,
Razz, and
Pomeg Berry (
Fuchsia).
HGSS
Green Shard
Can be traded for a
Leaf Stone.
RSE
Can be traded for
TM07 (
Hail).
DP
Can be traded for a
Aguav,
Lum, and
Rawst Berry (
Violet) or a
Wepear,
Hondew, and
Durin Berry (
Fuchsia).
HGSS
Blue Shard
Can be traded for a
Water Stone.
RSE
Can be traded for
TM18 (
Rain Dance).
DP
Can be traded for a
Chesto,
Oran, and
Wiki Berry (
Violet) or a
Bluk,
Kelpsy, and
Cornn Berry (
Fuchsia).
HGSS
Yellow Shard
Can be traded for a
Thunderstone.
RSE
Can be traded for
TM37 (
Sandstorm).
DP
Can be traded for a
Iapapa,
Aspear, and
Sitrus Berry (
Violet) or a
Pinap,
Grepa, and
Nomel Berry (
Fuchsia).
HGSS
2-The Shard Traders
This is the main use of Shards in the 4th Generation; the focus of this guide is to point out useful spots to farm Shards in order to maximize the Tutors efficiency.
The Tutors and their respective moves are the following:
3-Where to find Shards (and Star Pieces)
In every 3rd and 4th Generation game (with the exception of FRLG), you can find Shards in Pokéballs or via the Dowsing Machine, like any other item. (Star Pieces are avaiable in all games, including FRLG)
This section will
not cover these locations; instead, it will list re-usable spots for Shard-farming. The purpose of Star Piece-farming is explained here as well.
In RSE the only method to obtain Shards and Star Pieces other than finding them in the ground is via TM46-Thief, which can be found at Slateport Museum. The following Wild Pokémon can hold those items:

(Red Shard 5%)
(RSE) Ever Grande City / Route 128 - Super Rod (15%)

(Yellow Shard 5%)
(RSE) Route 124 / Route 126 - Dive (30%)

(Green Shard 5%)
(RSE) Route 124 / Route 126 - Dive (5%)

(Blue Shard 5%)
(RSE) Route 124 / Route 126 - Dive (65%)

(Star Piece 5% / Stardust 50%)
(RSE) Lilycove City - Super Rod (15%)
(LG) Cinnabar Island / Vermillion Harbour - Super Rod (40%)
It would be wiser to steal from them in Emerald, to abuse Compoundeyes' Field Effect, especially because the first 4 are unavaiable in FRLG. With Compoundeyes active, the chances of finding one holding a Shard (among all Pokémon) are as follow:
1,5%, 3%, 0,5%, 6,5% (in the same order)
For Staryu, the chances of finding one holding a Star Piece is 1,5% in Emerald (again with Compoundeyes), and 2% in LG. You can also steal Stardusts (worth 1000 in money), which will be held 75% of the time with Compoundeyes.
In DPPt, however, Wild Corsola, Chinchou, Relicanth and Clamperl are much rarer (usually Swarm Pokémon) and
do not hold Shards. Staryu still holds Star Pieces, but its rare as well, so Thief-farming isn't an option. Fortunately, there are several other options. You can:
-Dig them up in the Underground. Shards are Uncommon and Star Pieces are Rare (Very Rare before National Dex).
-Once per day, get a random Shard from this man at the Great Marsh entrance:
-Give Mr. Fuego a Star Piece to receive a set of four Shards (one of each color), at Fuego Ironworks. This is the
best method, since its arguably the fastest and can be done in Platinum.
And even though the Move Tutors are in Platinum, you can also get Shards reasonably well in HGSS:
-Randomly obtained via Rock Smash, in every location there are rocks to break.
-Obtained via the Dowsing Machine in the Pokewalker, in various courses. Night Sky’s Edge is the best course to do this, since it has all four Shards
and Star Pieces.
-And every Monday Morning, the Bargain Shop will be open at the Goldenrod Underground. It sells one of each of the following: Nugget, Stardust, Star Piece, Pearl, and Big Pearl. Each item is around 10% cheaper than their normal price. Star Pieces cost 4600.
4-Closing Words
I hope you found this guide informative and good to read. Please let me know of typos, mistakes or suggestions. I appreciate comeback - if people like it, I might write more guides in the future.
Huge thanks to
serebii.net,
psypokes.com and
bulbapedia.com for various images, screenshots and item icons. Also big thanks to the Official Pokémon Platinum Prima Guide, for Move Tutor info.
And my most sincere thanks to you, for reading it.
Vini, February 21th 2011.