✅ Answer: We know that according to narrations, wearing a gold ring and praying with it is prohibited for men, as mentioned in:

عَنْ رَجُلٍ عَنِ الْحَسَنِ بْنِ عَلِیٍّ عَنْ أَبِیهِ عَنْ عَلِیِّ بْنِ عُقْبَةَ عَنْ مُوسَی بْنِ أُکَیْلٍ النُّمَیْرِیِّ عَنْ أَبِی عَبْدِ اللَّهِ فِی حدیث قال: جَعَلَ اللَّهُ الذَّهَبَ فِی الدُّنْیَا زِینَةَ النِّسَاءِ فَحَرَّمَ عَلَی الرِّجَالِ لُبْسَهُ وَ الصَّلَاةَ فِیهِ الْحَدِیثَ

📚 Tahdhib, Vol. 2, p. 227

Imam Sadiq (peace be upon him) said in a hadith: 'Allah has made gold an adornment for women in this world, and He has forbidden men from wearing it and praying with it.'

Nowadays, platinum is referred to as white gold, although these two metals are different, and the rulings for gold should not be applied to platinum. However, based on the following narration, wearing a non-silver ring is generally discouraged:

عَنْ مُحَمَّدِ بْنِ یَحْیَی عَنْ أَحْمَدَ بْنِ مُحَمَّدٍ عَنِ الْقَاسِمِ بْنِ یَحْیَی عَنْ جَدِّهِ الْحَسَنِ بْنِ رَاشِدٍ عَنْ أَبِی بَصِیرٍ عَنْ أَبِی عَبْدِ اللَّهِ قَالَ قَالَ أَمِیرُ الْمُؤْمِنِینَ لَا تَخَتَّمُوا بِغَیْرِ الْفِضَّةِ فَإِنَّ رَسُولَ اللَّهِ صلی الله علیه و آله قَالَ مَا طَهُرَتْ کَفٌّ فِیهَا خَاتَمُ حَدِیدٍ

📚 Al-Kafi, Vol. 6, p. 468

Amir al-Mu'minin (peace be upon him) said: 'Do not wear a non-silver ring, for the Messenger of Allah (peace be upon him and his family) said: A hand wearing an iron ring is not pure.'

Based on the two narrations mentioned, wearing a platinum ring is discouraged, but its ruling differs from that of gold.