Certification Bodies in Pearl Grading

🌐 Pearl Certification

Pearl certification plays a vital role in ensuring the authenticity, quality, and value of pearls. At Nexus8gg, we source pearls that are carefully selected based on their luster, surface quality, shape, and color — and many of our premium pieces are certified or graded by internationally recognized laboratories.

However, not every piece of jewellery at Nexus8gg comes with a certificate as such certifications add significant cost to the final product. Instead, we focus on offering exceptional quality at a reasonable price, carefully handpicking each pearl based on our own strict standards.

We do offer a service to help customers send their purchased piece to NGI (Singapore Nan Yang Gem Institute) for certification. Please note that the cost of this certification will be borne by the customer.

*Please note: Nexus8gg only provides grading certificates from three reputable organizations — GUILD Gem Laboratories, Japan Pearl Science Laboratory (JPSL) & Singapore Nan Yang Gem Institute (NGI).

These certification bodies are known for their professional, independent grading standards.

🏛️ 1. GUILD Gem Laboratories (GUILD)

Location: USA & International
What They Do:
GUILD provides independent and professional gemological certification for pearls and other gemstones. Their pearl grading reports cover key quality aspects such as:

  • Luster (external and internal)

  • Surface (blemish and clarity)

  • Nacre thickness

  • Shape and color

  • X-ray and spectrometer validation

Why It Matters:
GUILD grading is respected for its transparency and scientific approach, helping buyers understand exactly what they're purchasing.

Website: https://www.guildgemlab.com

🧪 2. Japan Pearl Science Laboratory (JPSL)

Location: Japan
What They Do:
Founded in 1971, the Japan Pearl Science Lab is known for its thorough testing and certification of Japanese Akoya pearls. Their certification includes:

  • Luster grading (including internal glow)

  • Surface condition

  • Color, overtone, and matching

  • Nacre layer analysis

Why It Matters:
JPSL is one of the most trusted names in Akoya pearl certification, with decades of experience supporting the Japanese pearl industry.

Website: https://www.pearlscience.co.jp

🔬 3. Nan Yang Gemological Institute (NGI)

Location: Singapore

Overview:
NGI is a reputable gemological institute in Singapore offering certification services for pearls and other gemstones. Their pearl certification typically includes:

  • Surface and luster grading

  • Pearl type identification

  • Nacre and structural analysis

Website: https://www.ngi.com.sg/