Remove the silk curtain from the curtain rod. Lay it on a clean, flat work surface with the diffuser oil stain facing up.
Pour talcum powder onto the diffuser oil stain until it's covered. Leave the talcum powder on the surface of the silk curtain for 15 to 20 minutes to absorb the diffuser oil.
Brush the talcum powder off the surface of the silk curtains and into a trash can.
Moisten a clean cloth with white vinegar. Wring out the cloth to remove excess moisture. Dab at the remaining diffuser oil to break down the grease and deodorize the fabric.
Press a dry cloth into the silk fabric to absorb moisture.
Pour dry cleaning solvent onto another cloth. Sponge the silk curtain to remove the rest of the diffuser oil stain. Blot the stain with a dry cloth to remove the dry cleaning solvent.
Hang the curtain and allow it to air-dry.