ILNP Underground is a very warm-toned, very dark black with a sparkle finish. It is a permanent nail lacquer that retails for $10.00 and contains 0.4 oz.
ILNP Underground Holographic Nail Polish ($10.00 for 0.4 oz.) is a black base cream with larger holographic flakes that danced between warm orange, yellowy orange, green, and red with a hint of blue at times. It was slightly thinner than other shades I've tried, but it didn't impede the application as the color went on evenly, wasn't prone to pooling, and self-leveled as it dried down to a smooth, even finish.
Per the brand, it has its maximum coverage in three to four coats. In the swatches, I've applied two coats using Deborah Lipmann Gel Lab Pro base and top coats, which was sufficient for full coverage for the most part, so I'd say a third would be ideal. I wore this shade for 10 days and had minor tip wear and no chips.
FURTHER READING: Formula Overview, which is a detailed review of the range as a whole.
Butyl Acetate, Ethyl Acetate, Nitrocellulose, Adipic Acid / Neopentyl Glycol / Trimellitic Anhydride Copolymer, Acetyl Tributyl Citrate, Isopropyl Alcohol, Stearalkonium Bentonite, Acrylates Copolymer, Styrene / Acrylates Copolymer, Silica, Benzophenone-1, Trimethylpentanediyl Dibenzoate MAY CONTAIN Titanium Dioxide (CI 77891), Iron Oxides (CI 77489, CI 77491, CI 77492, CI 77499), Red 6 (CI 15850), Red 7 (CI 15850), Red 34 (CI 15880), Yellow 5 (CI 19140), Blue 27 (CI 75510), Black 2 (CI 77266), Mica, Aluminum Powder (CI 77000)
Disclaimer: Ingredient lists are as available by the brand (or retailer) at the time of publishing. Please always check product packaging, if it exists, for the ingredient list applicable to the product you're purchasing, or the brand or retailer's website for the most up-to-date ingredient list.