You can get it at the Pokemon mainson
When you meet up with Cheryl in the Eterna Forest. When you and her reach the exit, she'll thank you and give you a Soothe Bell as a gift.
You find a soothe bell at the Pokemon mansion
The are NO soothe bells you can BUY in Pokemon Diamond. but if you want you can even get a Soothe Bell for free in Pokemon Diamond, just walk to the Pokemon Mansion and walk into the rooms, one of the rooms contains a soothe bell. Hope this helps.
Soothe Bell
in one of the tall buildings at hearthome
You get it from a lady in the left wing of the Mansion.
You can get Soothe Bells from the Pokemon Mansion.
The soothe bell (sometimes confused with south bell) is an item in Pokémon Diamond. You can get it at the Fan Club in Hearthome City.
Heals your Pokemon when you make impact on another Pokemon (you hit it).
You can't get a Soothe Bell in Gold, but you can get the Soothe Bell by trading with Jasmine in Heart Gold.
thare is no soothe bell in gold.
The soothe bell is found in the Pokemon Mansion on route 212. The soothe bell is given to the player by the maid on the second floor.