Nothing substitutes for a good consultation with a professional colorist but if you find yourself in the haircolor aisle with a puzzled look on your face, this may shed some light. Other than the new Color by Robert Craig, permanent haircolor containing peroxide and ammonia is capable of lightening, darkening and covering grey hair 100%. Permanent products contain ammonia and are mixed with peroxide to activate the color. It does fade and will need to be touched up within 4 to 8 weeks depending on how fast your hair grows and how far away you move from your natural color. Color by Robert Craig fades very little, covers grey and does not lighten the hair nor does it do any damage to the internal structure of the hair as it colors because it does not contain the peroxide and ammonia that other permanent dyes do. A demi-permanent color cannot lighten hair, can darken, adds subtle tones and can blend up to 25% grey. Demi's do not contain ammonia but are mixed with a low level of peroxide to activate the color. It lasts almost as long as a permanent color and can be even more permanent when heat is used during the process. On permed or color treated hair a demi-permanent can become permanent. A semi-permanent cannot lighten hair, can darken, will blend or cover some grey and with repeated applications may not wash out of the hair completely. Semi's do not contain ammonia or peroxide. On permed or color treated hair a semi-permanent can become permanent. For examples and help in choosing a color and product, be sure to check my on-line consultation.