Here are some ways to say it:
* Platinamu: This is the most direct translation, using the English word and simply adding the Swahili suffix "-amu" to make it sound like a Swahili word. This is common for scientific or technical terms.
* Chuma cha Platinamu: This translates to "platinum metal" and is a more descriptive way to refer to it.
* Dhahabu Nyeupe: This translates to "white gold," which is sometimes used to refer to platinum.
Ultimately, the best way to say "platinum" in Swahili will depend on the context and who you're speaking to.