Other highly rated stocks in the group includeMohawk Industries ( MHK ),Masco ( MAS ),Headwaters ( HW ) andAcuity Brands (AYI). But gross margin fell to 43.7% from 44.5%, due partly to lower-margin fabrication and installation revenue from Ikea, as well as some foreign exchange headwinds and modest cost inflation. Starting With Stone It makes slabs from a mixture of ground quartz aggregates, pigments and polymers, and claims that the surfaces are hard, nonporous, scratch- and stain-resistant and durable.