As of my last knowledge update in September 2021, several companies were known for offering Lab Diamonds Jewelry of high quality. However, the "best" lab-grown diamond jewelry company can vary depending on your specific preferences, budget, and the type of jewelry you're looking for. Here are a few reputable companies that were well-regarded at that time:

1. Brilliant Earth: Brilliant Earth is known for its ethically sourced lab-grown and natural diamonds. They offer a wide range of engagement rings, wedding bands, and other jewelry made with lab-grown diamonds.
2. James Allen: James Allen is an online jeweler that offers a variety of lab-created diamond engagement rings, earrings, and other jewelry. They provide high-quality images of their diamonds to help you choose the perfect stone.
3. Clean Origin: Clean Origin specializes in lab-grown diamond engagement rings and wedding bands. They focus on offering ethical and environmentally friendly options for consumers.
4. Ada Diamonds: Ada Diamonds is known for its custom lab-grown diamond jewelry, including engagement rings and bespoke designs. They have a strong emphasis on sustainability and craftsmanship.
5. Pure Grown Diamonds: This company produces lab-grown diamonds with a focus on quality and transparency. They offer a range of jewelry options, including engagement rings and earrings.
6. Miadonna: Miadonna is another company that offers lab-grown diamond jewelry with a strong commitment to ethical and sustainable practices. They have a variety of styles and options to choose from.

Please note that the landscape of the lab-grown diamond industry may have evolved since my last update, with new companies entering the market and existing ones refining their offerings. It's essential to do your own research, read reviews, and compare prices and options before making a purchase to ensure you're getting the best lab-grown diamond jewelry that meets your specific needs and values. Additionally, be sure to check for the latest reviews and recommendations to find the most up-to-date information on reputable companies in the industry.