Sinnoh-Stein - Evolution Item
Dieser spezielle Stein, der ursprünglich in der Sinnoh-Region gefunden wurde, löst bei bestimmten Pokémon die Entwicklung aus. Er ist sehr hart und hat einen schönen Glanz.
Special evolution items like the Sinnoh-Stein first arrived back with the second generation of Pokémon, and are now required when evolving Pokémon such as Schlurplek and Rihornior and Tangoloss and Elevoltek and Magbrant and Togekiss and Ambidiffel and Yanmega and Kramshef and Traunmagil and Skorgro and Snibunna and Mamutel and Porygon-Z and Galagladi and Roserade and Zwirrfinst and Frosdedje. When evolving these Pokémon, this item is required in addition to the candy, and is consumed when used.
How to get the Sinnoh-Stein

The Sinnoh-Stein is obtained from spinning Pokestops and Gyms. There is a very low drop chance of around 1% per spin to receive a Sinnoh-Stein or any of the other evolution item, and there is an equal chance of obtaining each of the 5 currently available items.
There's no way to ensure that the Sinnoh-Stein will drop, but with only 4 other items, there's a greater than 50% chance that you'll receive one once you've spun over 250 Pokéstops.
The 7th day streak bonus gives you a very high chance of obtaining one of the evolution item, but it's not believed to be guaranteed.
Other evolution items
The other evolution items that can be found in Pokemon GO are: