Determining the stressed word in a sentence when using possessive

Generally, content words are stressed and function words are not.

When speaking naturally you would say:

This is the DOG'S COLLAR.

There is syllabary stress on the first syllable of COL-lar.

This is the DOG'S BLUE COLLAR.

My first thought was to stress BLUE more than dog's and collar, because it seems to add information about which one of the collars you are referring to: the blue collar as opposed to other coloured collars. It seems there are other collars as well. Otherwise, I would stress DOG'S more than blue and collar, but it could entirely depend on dialect or local speech.

"collar" gets the highest stress in "This is the dog's collar." There are variations and options to consider, though.

Understanding numbers 0, 1, 2, ... to indicate stress (or pitch) levels, with 0 for "no stress", 1 for highest stress, 2 for next highest, 3 for third highest, and so on, the most normal contour in English, depending on the number of stressed syllables, is from the family of contours: 1, 2 1, 2 3 1, 2 3 4 1, etc., or else (especially when the the last stress comes all the way at the end), the same contour but with a low level stress (say about 3) at the end: 1 3, 2 1 3, 2 3 1 3, 2 3 4 1 3, and so on.

A long time ago, I proposed that the above holds for any sequence of constituents, be they syllables, words, or phrases (see English Word Stress and Phrase Stress). This can be interpreted cyclically, as proposed in The Sound Pattern of English, so that the stresses of a constituent can all be lowered and that constituent embedded inside another.