As of my last knowledge update in September 2021, specific local businesses or retailers in Parramatta, Australia, that offer lab-grown diamonds might have changed or expanded since then. It's a good idea to conduct a current online search or directly contact local jewellery stores in Parramatta to inquire about their selection of lab-grown diamonds. Here are some general steps you can take to find lab-grown diamonds in Parramatta:

1. **Online Search:** Use search engines to look for jewellery stores in Parramatta that specialize in lab-grown diamonds or ethical jewellery. Use keywords like "lab-grown diamonds Parramatta," "ethical jewellery Parramatta," or "sustainable diamonds Parramatta."

2. **Jewellery Stores:** Visit local jewellery stores in Parramatta and inquire if they offer lab-grown diamonds. Even if lab grown diamonds Parramatta a store doesn't display lab-grown diamonds prominently, they might have options available upon request.

3. **Contact Retailers:** Contact well-known jewellery retailers or chains in Parramatta and ask if they have lab-grown diamonds in their inventory.

4. **Online Retailers:** Explore online jewellery retailers that offer lab-grown diamonds and provide shipping to Parramatta. Many reputable online stores offer a wide range of options.

5. **Custom Jewellers:** Consider working with custom jewellers who can create a unique lab-grown diamond piece according to your specifications and preferences.

When contacting or visiting jewellery stores, consider the following:

- **Certification:** Ask about the certification of the lab-grown diamonds. Reputable diamonds should come with certification from recognized gemological laboratories like the Gemological Institute of America (GIA) or the International Gemological Institute (IGI).

- **Quality:** Inquire about the quality of the lab-grown diamonds, including the 4Cs (carat weight, cut, color, clarity).

- **Ethical Sourcing:** If ethical considerations are important to you, ask about the store's commitment to ethical and sustainable practices in the diamond industry.

- **Price Range:** Discuss your budget and explore options within that range. Lab-grown diamonds are often more affordable than natural diamonds, offering good value for your investment.

Remember that the availability of lab-grown diamonds in Parramatta may vary, so it's best to directly contact or visit jewellery stores for the most accurate and up-to-date information.