Can you wash cashmere that says dry clean only?

Yes, you can.

Follow these simple steps to care for your cashmere lingerie and clothing:

Hand-washing or gentle machine-washing are safe for cashmere.

1. Use cold water only. Warm water will shrink fragile cashmere wool and make the garment unwearable.
2. Use mild detergent with lanolin. Lanolin oil is a waxy substance derived from sheep's wool. Its' excellent emollient properties will straighten natural hair fibre keeping it soft and shiny. 
3. Do not use dryer. Drying your cashmere garment even on cold setting will felt and change the structure of cashmere or wool fibre. Instead, gently squeeze out extra water and lay flat on a towel in a well-ventilated area away from direct sun.

High quality cashmere is softer and lighter,  providing up to three times more insulating than sheep wool. The quality of cashmere is graded on its fineness and hair length, making it one of the most sought after commodities of today's fashion industry.