When silver is ingested with proteins or other compounds, it can lodge in the skin. But there seems to be only minor uptake of silver in cremes as there is a prescription ointment containing silver that is used on very sensitive skin as around tracheotomy sites. As it contains silver, it does darken when exposed to light.

I think it's a great idea to preserve your goodies with silver colloid although I will note a tiny amount of Ascorbic Acid might be an option for some products, especially exfoliants. Caprylic Acid, an antifungal, is wisely used in many cosmetics and would preserve the product from fungal overgrowth and kill topical fungus on the skin, especially for the scalp, the prime nexus for external yeast/fungal invasion. God bless!