Black Diamond Serum

The base most products are built on. It carries the other ingredients and has no safety concern.

A humectant that draws water into the skin. One of the best-studied, best-tolerated ingredients in personal care.

A fast-evaporating solvent used to carry actives and give toners a light, "clean" feel; at the concentrations used in classic astringents it can be genuinely drying or irritating with repeated use, especially on dry or compromised skin, though it is not inherently toxic and is a normal, well-studied cosmetic ingredient.

A synthetic ester used to thin out heavy formulas and help other ingredients absorb faster. It is considered safe as used by CIR, but it has a reputation among acne-prone users for feeling occlusive on skin, so people who clog easily may prefer to patch test or choose lighter alternatives.

A humectant sugar alcohol that draws water into the skin. It is well tolerated and widely used in skincare and food. Not known to cause concern at the concentrations used in cosmetics.

A form of vitamin B3 used to support a more even-looking tone and a comfortable barrier. Well tolerated at cosmetic levels.

This is a stable, water-soluble derivative of vitamin C that converts to ascorbic acid in skin and is used for antioxidant and brightening support. It is generally better tolerated than plain ascorbic acid and has a low reported rate of irritation in formulation testing.

A humectant that holds water at the skin surface for a more hydrated look. No safety concern.

A soothing plant extract traditionally used in skincare, valued for its potential anti-inflammatory properties. Published assessments note it is generally well tolerated in cosmetic formulations, though people with sensitivities to botanicals may want to patch test.

A plant extract long used in traditional wound care and now common in "cica" soothing products, valued for calming redness and supporting the skin barrier. It is generally well tolerated, with rare contact allergy reported.

Plant-derived sterols that function as emollients and barrier-supporting ingredients found naturally in many botanical sources. They are well tolerated in cosmetic formulations with no known safety concerns at typical use levels.

A common preservative and fragrance/solvent ingredient found naturally in many essential oils. It is well tolerated by most people at the levels used in cosmetics, but it is one of the 26 EU-designated fragrance allergens and can trigger reactions in people with an existing sensitivity.

Carbomer is a synthetic polymer used purely to thicken and stabilize gels and lotions, with negligible skin penetration due to its large molecular size. Safety reviews have found low toxicity and minimal irritation potential even in leave-on use.

A polysaccharide produced by yeast fermentation used as a film-former and thickener in serums and gels. Its safety profile is supported by extensive use in food and cosmetic applications.

Caprylyl glycol is a plant-derived humectant that also has mild antimicrobial properties, so it is commonly paired with other preservatives to allow lower overall preservative levels. Available data do not point to meaningful irritation or sensitization concerns at typical use levels.

A glycerin derivative used as a skin conditioner and preservative booster, often paired with phenoxyethanol to allow lower total preservative levels. It has a low irritation and sensitization profile in safety reviews.

A lightweight, odorless emollient made by combining coconut or palm-derived fatty acids with glycerin. It spreads easily, feels non-greasy, and has a long history of use in skin and hair products with no meaningful irritation or sensitization signal.

Pentylene glycol is a humectant and solvent that also offers mild antimicrobial support in formulas. It is generally well tolerated, with only rare reports of irritation, mostly in already sensitive or compromised skin.

Xanthan gum is a microbial-fermentation-derived polysaccharide used to thicken and stabilize textures, similarly common in food. Cosmetic panel review of this and related microbial gums found them safe as used, with no meaningful irritation signal at typical concentrations.

A strong alkali used in tiny amounts to adjust the pH of cosmetics to safe, skin-friendly levels. At the pH found in finished products, sodium hydroxide is neutralized and well tolerated.

A phospholipid emulsifier from soy or sunflower that binds water and oil and helps other ingredients absorb. It is a natural component of skin membranes, well tolerated, and reviewed as safe as used; a soy-derived grade is not a meaningful concern for a soy food allergy because the protein is largely absent.

A mild plant-derived emulsifier combining polyglycerol and lauric acid. Used in gentle formulas to blend oil and water phases; well tolerated across skin types at cosmetic concentrations.

A plant-derived emollient and preservative formed from glycerin and caprylic acid (coconut) that helps retain moisture and supports formula stability through mild antimicrobial activity.

Used in tiny amounts to set a product to skin-friendly pH. No concern at those levels.

The sodium salt of benzoic acid, used as a preservative in both foods and cosmetics. Decades of safety review support its use at typical cosmetic concentrations, with mild irritation the main reported issue in sensitive skin.

A larger, gentler alpha hydroxy acid than glycolic acid, used to exfoliate and to draw in moisture. It can still cause stinging or increased sun sensitivity at higher concentrations, so daytime SPF use is sensible, but it is generally better tolerated than glycolic acid.

A widely used, gentle preservative also common in food. It is generally well tolerated, though it can occasionally cause mild, transient irritation in people with already-compromised or very reactive skin.

An undisclosed scent blend that can contain dozens of components. The single most common cause of cosmetic contact allergy, and the blend is not itemized, so you cannot see what is in it.