Sonnet Practice

My mistress' eyes are nothing like the sun;
Coral is far more red than her lips' red;
If snow be white, why then her breasts are dun;
If hairs be wires, black wires grow on her head.
I have seen roses damask'd, red and white,
But no such roses see I in her cheeks;
And in some perfumes is there more delight
Than in the breath that from my mistress reeks.
I love to hear her speak, yet well I know
That music hath a far more pleasing sound;
I grant I never saw a goddess go;
My mistress, when she walks, treads on the ground:
And yet, by heaven, I think my love as rare
As any she belied with false compare.

Determine whether it's Petrarchan or Shakespearean.  Explain where the shift is and how it influences the overall theme and tone of the work.  

1.  Petrarchan Sonnet: "a sonnet form popularized by Petrarch, consisting of an octave with the rhyme scheme abbaabba and of a sestet with one of several rhyme schemes, as cdecde or cdcdcd."
2. Shakespearean Sonnet: "a sonnet form used by Shakespeare and having the rhyme scheme  abab, cdcd, efef, gg." 

By the rhyming scheme it is easy to see that this is a Shakespearean Sonnet, it follows the rhyming pattern, as stated in the definition, directly and exactly. The shift in the sonnet begins at "And yet, by heaven, I think my love as rare" and ends with "As any she belied with false compare." At this point in the sonnet the narrator ceases to describe the person as regular, or as nothing special, because at first it was as though everything in the world was better than her. At this point, although it is the end, the narrator ceases to critique the woman and her looks and instead focuses on his love for her. It changes the theme to something of romantic aspirations, the tone changes to a more loving one, one that forgives flaws, or comparisons to other people, and instead focuses on the one person they (the narrator) truly loves.