Four-Cs is a specialist diamond jewelry store in Wakayama City, Japan, offering imported diamonds and fine jewelry at accessible prices. The brand emphasizes quality and value, with diamond prices described as among the lowest in the industry. Its collection includes diamond jewelry, made-to-order engagement rings, and wedding rings from domestic Japanese manufacturers. Customers can choose diamond grades and designs for custom-made engagement rings and jewelry; ready-made pieces are not generally available in the store. Four-Cs also operates an online shop, allowing customers farther away to browse and purchase, with prices and services stated to match those offered in-store.

The store provides after-sales care for items purchased from Four-Cs, including complimentary ultrasonic cleaning and basic polishing, along with ring resizing services subject to the applicable terms. More extensive professional refinishing is also available. Located about a 20-minute walk from Wakayama Station, the shop has three dedicated parking spaces. Daytime visits do not require reservations, while evening appointments are by reservation.