From their own website:
(Emphasis mine)
Just lookin' out for you!
Kalevala Jewelry
Instructions from Kalevala website:
Silver Jewelery
Use a polishing cloth to clean slightly tarnished Kalevala Koru silver jewelery. Polishing cloths are available in jewelery shops. More heavily tarnished pieces of jewelery can be cleaned with polishing paste for silver. To avoid removing the oxide from the piece, the paste should not be spread too thickly. Apply the polishing paste with a soft cloth and clean the jewelery piece. To prevent the paste from causing stains on clothing, rub the paste off and wash the piece with water and mild washing-up liquid. Chains can also be cleaned as instructed above.
We do not recommend liquid silver polish. Pearls should not come in contact with silver polish.
Bronze Jewelery
Bronze - an alloy of copper, tin and zinc - oxidizes and tarnishes more easily than precious metals. Bronze jewelery is lacquered with a galvanic coating at our factory. However, with skin contact, this coating can wear off and cause the jewelery piece to tarnish. Tarnished areas can be polished with a special cloth, available in jewelery shops. Copper and brass cleaner can also be used.
General
Stones set in Kalevala Koru jewelery should not be rubbed with cleaning agents.
Ball-shaped pieces and badly tarnished jewelery can be sent to the Kalevala Koru factory for complete cleaning and restoration. A small fee is charged for this service. After restoration, the jewelery will be easy to polish with cleaning agents and with a wash with water afterwards. The green patina is a natural feature of old and antique jewelery.
Do not expose jewelery to hair spray or perfume. Jewelery should not be worn in the sauna or steam room, or in chlorinated or salt water.
Gold, silver and bronze jewelery should all be washed occasionally with water and mild washing-up liquid. This keeps dirt from collecting and helps prevent tarnish.
Kalevala Koru jewelery does not contain nickel.
(Emphasis mine)
Just lookin' out for you!