MAC Rainbow Interlude is a slightly cool-toned, very light pink with a sparkle finish. It is a limited edition lipgloss that retails for $18.50 and contains 0.1 oz.
MAC Rainbow Interlude Lipglass ($18.50 for 0.10 fl. oz.) is a translucent pink with pink and silver pearl. It had sheer coverage and lightened my natural lip color a bit while adding more of a pink tint to them, but the effect that was more noticeable was the sparkle and shine. The texture was smooth, somewhat tacky, but comfortable to wear and easy to spread across the lips. It lasted for three hours on me.
Worth noting, the Lipglasses in this collection contain significantly less product than regular Lipglass--the tube may seem thicker, but it's likely due to thicker plastic. MAC Lipglass typically contains 0.16 fl. oz. and retails for $16 (or $100.00/fl. oz.), while this one is $18.50 for 0.10 fl. oz. (or $185.00/fl. oz.). The tubes are very similar to the kind that Dazzleglasses and Cremsheen Glasses come in. None of the glosses were described as sheer (Lipglass is a "high coverage" formula, per MAC's website), so none of them rated very well, though I think a few would work for layering or sheerer lip looks, if that's something you like!
FURTHER READING: Formula Overview, which is a detailed review of the range as a whole.
Our classic Lipglass you adore is getting a makeover! Now in a double-walled clear vial, M∙A∙C Lipglass is chicer than ever. This unique gloss is available in an even bigger batch of colours with 57 over the rainbow shades – all of which provide a high-gloss, glass-like finish or subtle sheen. The pigmented product also features our new Oilshine Moisture Complex – a yummy blend of babassu, coconut, apricot and jojoba oils – to help soften and condition lips.