The concentration of a colloidal metal or colloidal mineral in a liquid is indicated by ppm, which is equal to parts per million, which in turn is equal to the number of milligrams per liter (mg / l). The only good method to measure the concentration is through ICP (Inductive Coupled Plasma). You will find a good explanation of this measuring principle in the Report from Hogeschool Zuyd on colloidal gold.
It is almost unbelievable but you can calculate it yourself. When you distribute 2 liters of Crystal colloidal silver over 1 hectare (10,000 m2), you have 1.1 billion particles of silver per square millimeter (mm2). This incredible number is caused by the small particle size of our product, namely 0.65 nanometers. If the particle size would be 650 nanometers, then in the above example you only had 1 particle per square millimeter (mm2).