conditional phrases and series

If I said, "I will buy a designer handbag, Belgian chocolate, and a diamond ring if I get promoted."

Does the phrase "if I get promoted" apply only to the diamond ring? Why or why not?" My understanding is that the "if" conditional needs to apply to an independent clause so that the "if" clause applies to "I will buy a designer handbag, chocolate, and a diamond ring."

From a grammatical point of view, it's actually not quite unambiguous - the punctuation rules about sequential and command a comma before the and before a diamond ring but that comma could also be read as a stop that might separate a diamond ring from the other items.

But in practice, most everyone would realize that your conditional is about all three of these items, unless you make it quite clear (using speech melody when spoken, or maybe a semicolon in writing) that a stop is indeed intended.

It could be taken humorously to mean the first two items anyway and the third on condition, but that would rather be used tongue in cheek/as quibbling wordplay - I imagine you could be benignly mocked this way if the opportunity presented itself (as in, you can, or will, afford the diamond ring only if you get promoted?).

But as a matter of how you would generally be understood, most people would assume you are subjecting all three items to the condition.