media query pixel-density and max-width together

Question

I'm trying to create a rule that includes/excludes based on both max-width and device-pixel-ratio. An example would be if I want the Kindle Fire @ 600px to be excluded, but the iPhone5 @640 (smaller real world screen) to be triggered.

Does the following make an AND or an OR rule? Assuming it makes an OR rule, how would I create a rule that performs an AND type function (must pass both 'device-pixel-ratio of 2' AND 'max-width 749px' checks to be triggered)

@media only screen and (min--moz-device-pixel-ratio: 2), 
        only screen and (-o-min-device-pixel-ratio: 2/1), 
        only screen and (-webkit-min-device-pixel-ratio: 2), 
        only screen and (min-device-pixel-ratio: 2),
        only screen and (max-width: 749px){
        }

EDIT BELOW:

Okay here is what I have so far - I'm guessing commas are OR and 'and' is obviously AND. Is this correct? I'm trying to make a more universal set of queries targeting more than just iPhones/iPads...

@media
only screen and (max-device-width : 721px) and (orientation : portrait) and (-webkit-min-device-pixel-ratio: 1.5),
only screen and (max-device-width : 721px) and (orientation : portrait) and (min-device-pixel-ratio: 1.5),
only screen and (max-width: 359px) {
/* All Portrait Phones */
}

@media
only screen and (min-device-width : 360px) and (max-device-width : 999px) and (-webkit-min-device-pixel-ratio: 1.5),
only screen and (min-device-width : 360px) and (max-device-width : 999px) and (min-device-pixel-ratio: 1.5),
only screen and (max-width: 999px) {
/* Small tablets (assume vertical) and landscape phones */
}
/*note - Anything over 999 wide to render fully - desktop, landscape or large tablets */

Answer 1

Use mediaqueries like this example for iPad with Retina display.

@media only screen 
and (min-device-width : 768px) 
and (max-device-width : 1024px) 
and (orientation : portrait)
and (-webkit-min-device-pixel-ratio: 2) { /* STYLES GO HERE */ }