Silver, gold, diamond etc are segment which are categorized for providing services, freebies, etc to client basis their relationship value.....whereas risk categorization is different thing. It is generally not visible to the end customer, but is done internally by the bankers basis the risk profile of the customer....Appriciation for your reference ☝️.
On a Saving Account side SBI classify silver, gold, diamond Linked to Privilege, benefits.
like @CosmicCat mentioned, it is mentioned at the time of customer ID creation basis the profile of customer like occupation, nature of income, type of business, type of entity (for non-individual), mode of relationship establishment, etc etc