Colorado HP T-Grade Bluegray is a Quartz product for plaster finishes. CO-HP T-Grade Bluegray from our Colorado plant offers a closer source to west coast markets. The T-Grade material from the Estes Colorado plant allows you to add the right amount of aggregate to your plaster Finish to get your desired finish. Estes Quartz is sold as a site mix product. The advantages of site mix allow you to customize finishes to customer specifications, avoid lot # matching issues with pre-mixed products, and offers savings over pre-mixed products. CO-HP T-Grade Bluegray from Colorado plant contains small amounts of mica flakes that provide a sparkle to your plaster finishes.