To convey the idea of luxury, your fashion logo must embody elegance and beauty. Think monograms with thin typeface, or wordmarks with fine details in the lettering.
Or, eschew words and letters altogether for geometric shapes. You can go for a bold look with strong, sharp angles, or something more graceful with swooping, spiraling lines.
Consider
color, as well. Gold is a classic indicator of wealth and luxury, but don’t feel forced into that box. Silver, platinum, even jet black will also serve, with the right product.