MAC Silver Dusk is a moderately warm-toned, very light beige with a sparkle finish. It is a limited edition highlighter that retails for $29.00 and contains 0.42 oz.
MAC Silver Dusk Iridescent Powder/Loose ($29.00 for 0.42 oz.) is a soft beige with subtle, warm undertones and flecks of sparkle and finer pearl strewn throughout. I found that it had larger sparkle in it than Golden Bronze, though the effect was similar on the skin: glowing, luminous, but not metallic or in pore-emphasizing territory. There were a few bits of sparkle on my skin, which I know some love and some loathe.
The powder had a soft, silky consistency but didn't disperse too readily into the air (sometimes those loose powders can be too airy in a way), so it was easy to apply more or less depending on how intense I wanted the finish to be. I didn't feel like it was a product where I had to apply a lot of layers to get to intense shine but I was just as easily able to achieve a subtle glow if preferred. As it was beige, it didn't really add "color" to my skin, though I could see the lighter base brightening the area I applied it to. It went on evenly, blended out almost on its own, and lasted well for eight hours.
FURTHER READING: Formula Overview, which is a detailed review of the range as a whole.
M·A·C Iridescent Powder/Loose is a finely milled mixture of mica and pigments that gives skin a subtle glaze of colour with intense pearl. It can be used on its own or mixed into other products like foundations or moisturizers to enhance their iridescent qualities. Designed to apply easily and uniformly, it blends beautifully and can be applied on bare skin or over foundation. Because it's so concentrated, it should be used sparingly at first.