Pearl (Moti) Buying Guide: Types, Quality, Keshi and Price
“Pearl (Moti) is the gem of the Moon in Vedic tradition, and almost every pearl sold today is cultured. Learn the main pearl types, what decides quality, why keshi pearls are solid nacre, how to spot imitations, and what pearls cost.”
Pearl, known in India as Moti, is an organic gem grown inside a living mollusc, and has long stood for purity and calm. In Vedic tradition it is the gemstone of the Moon (Chandra). Almost every pearl sold today is cultured — a real pearl, grown with human help — and natural pearls such as the famous Basra are now collector's items. This guide explains the main pearl types, the factors that decide value, how keshi pearls differ, how to tell a real pearl from an imitation, and how to look after one.
Quick answers: Pearls are soft (Mohs about 2.5–4.5) and are damaged by acids, perfume and cosmetics. Lustre is the most important quality factor. Keshi pearls have no bead inside and are solid nacre. At Ratna Gems, freshwater cultured pearls cost ₹150 per carat and keshi pearls mostly ₹450 per carat, each with an independent laboratory report (October 2026) — see the Pearl collection.
Pearl (Moti) Gemmological & Physical Specifications
| Gemstone Type | Organic (Nacreous, formed in bivalve mollusks) |
| Chemical Composition | Aragonite (Calcium Carbonate, CaCO₃) micro-crystals bound by Conchiolin (organic protein matrix) |
| Ruling Planet | Moon (Chandra) |
| Mohs Hardness | About 2.5 - 4.5 (soft; easily scratched and damaged by acids) |
| Specific Gravity | 2.60 - 2.85 |
| Refractive Index | 1.52 - 1.69 |
Moti in Vedic Tradition
In Vedic tradition, pearl is the gemstone of the Moon (Chandra), traditionally associated with a calm, settled mind. Many astrologers advise against setting a pearl together with Emerald (Panna) or Cat's Eye. The customs below are the ones most often followed; whether a stone suits you, and at what weight, is for your own astrologer or Pandit ji to advise.
Traditional Moti Wearing Customs
| Planet | The Moon (Chandra), ruler of Cancer (Karka) in Vedic astrology |
| Finger | Little finger (Kanishtha) of the working hand |
| Metal | Silver |
| Customary Day | First worn on a Monday morning during Shukla Paksha, after a rinse in Gangajal and raw milk |
| Associated Mantra | "Om Chandraya Namah" (ॐ चंद्राय नमः) |
A Guide to the World's Most Famous Pearls
Understanding the different types of pearls is the first step to making an informed choice. Each has a unique story, character, and value.
Comparison of Major Pearl Types
| Pearl Type | Mollusk Species | Size (Typical) | Natural Colors | Luster & Growth Characteristics |
|---|---|---|---|---|
| Basra (Natural) | Pinctada radiata (Persian Gulf) | 3 - 8 mm | Creamy White, Silvery-white | Natural pearls, now very rare; Gulf pearling collapsed in the 1930s. |
| South Sea (Cultured) | Pinctada maxima (Indo-Pacific) | 9 - 20 mm | Silver-lip (White/Silver), Gold-lip (Golden) | Largest sizes; thickest nacre of all cultured pearls; satiny luster. |
| Akoya (Cultured) | Pinctada fucata martensii (Japan) | 6 - 9 mm | White, Pinkish overtones | Japan cold coastal waters slow growth, creating dense aragonite layers with mirror luster. |
| Tahitian (Cultured) | Pinctada margaritifera (French Polynesia) | 8 - 14 mm | Charcoal, Grey, Peacock (Green/Rose) | Grown in black-lip oysters; prized peacock grade has deep natural overtones. |
| Keshi (Byproduct) | Byproduct of pearl culturing (no bead nucleus) | 2 - 10 mm | Silvery, Golden, Grey | Solid nacre with no bead inside; usually baroque or button shapes; often high lustre. "Keshi" is Japanese for poppy seed. |
| Freshwater (Cultured) | Hyriopsis cumingii (Mussel) | 4 - 12 mm | White, Pink, Peach, Lavender | China is the main source; most are grown from tissue alone and are solid nacre. |
The Legend of the Basra Pearl: The Basra Moti is not a cultured pearl; it is a natural pearl from the Persian Gulf. For centuries, these were the most prized pearls in the world. The Gulf pearl trade collapsed in the 1930s, undercut by Japanese cultured pearls and the Great Depression, and natural Basra pearls are now very rare collector's items. They are often irregular in shape with a unique creamy color and a soft, inner glow. Buyers who follow tradition prize them above all other pearls, but their rarity and price make them almost impossible to find today.
How to Buy a Quality Pearl, Step by Step
Step 1: Evaluate the Luster
Luster is the single most important quality factor. It is the deep, mirror-like or satiny glow produced as light reflects from the thin overlapping layers of nacre. High-quality Japanese Akoya pearls display a sharp, mirror-like reflection, whereas South Sea pearls display a deep, satiny glow. A quality pearl should show a clear reflection of the observer on its surface.
Step 2: Assess the Surface Quality
As organic gems, pearls naturally contain minor surface growth marks, pits, or wrinkles. The cleaner the surface, the higher the value. The finest pearls look clean to the eye, with no obvious pits, spots or wrinkles.
Step 3: Consider the Shape
While perfectly spherical rounds command the highest prices, baroque (irregular) pearls like drop, button, and Keshi have immense aesthetic appeal. For rings and pendants, a well-shaped button or baroque pearl can be both attractive and good value.
Step 4: Understand Nacre Quality
Nacre is the calcium carbonate substance secreted by the mollusk. Thick nacre gives better lustre and lasts longer; thin nacre over a bead can wear through. Keshi pearls are unique because they have no bead nucleus inside, consisting of 100% solid nacre.
Step 5: Verify Authenticity (Natural vs. Cultured vs. Fake)
- Natural Pearls: Formed without human intervention in the wild. Exceptionally rare, priced by weight.
- Cultured Pearls: a cultured pearl is grown inside a mollusc with human assistance — a tissue graft, with or without a shell bead nucleus, is introduced and the mollusc then does exactly what it does in the wild, laying down nacre for years. The nacre is real nacre. The animal is a real mollusc. What was assisted is the starting point, not the pearl.
- Diagnostic Authenticity Tests:
- The tooth test: rubbed gently against the edge of a front tooth, a real pearl — natural or cultured — feels slightly gritty, while glass and plastic imitations feel smooth. It separates real from imitation only, not natural from cultured.
- Laboratory Radiography: The most reliable method. An X-ray or CT scan reveals the concentric organic growth rings of a natural pearl versus the solid shell bead nucleus interface of a cultured pearl.
The fact that decides most pearl purchases in India. Natural pearls — Basra and the like — effectively left the commercial market in the 1930s. What survives is mostly antique, sold at auction, and priced accordingly. Every major pearl house in the world today sells cultured pearls, in one variety or another, and has done for the better part of a century. So the practical question is never "natural or cultured" — it is which cultured type, what nacre thickness, and what lustre.
Where Keshi sits, and why it matters for a Moti. A standard cultured pearl is a thin skin of nacre over a round shell bead. A Keshi pearl has no bead at all — it forms when the mollusc rejects the bead or when a pearl grows from a piece of the graft tissue alone, so it is solid nacre right through. In structure that is the closest any cultured pearl comes to a natural one, which is why buyers who follow tradition often ask for keshi. They are usually baroque rather than round, and that irregularity is the honest signature of a pearl with nothing inside it.
Crucial Chemical Care Warning: Pearls are highly vulnerable organic gems. Because they are composed of calcium carbonate, they will react and fizz (dissolve) when exposed to weak acids like vinegar. Furthermore, the organic conchiolin protein binder is easily stripped and degraded by alcohols, cosmetic solvents, perfumes, and hairsprays—leading to yellowing and permanent dullness. Always follow the "Last On, First Off" rule: apply cosmetics and perfumes first, and wear your pearls last.
Step 6: Understand Weight and Price
Pearl prices depend on type, lustre, nacre, surface, shape and size. Weight is given in carats or in the traditional Indian Ratti:
- Conversion: 1 pakki Ratti = 0.182 grams = 0.91 carat (and 1 carat = about 1.10 Ratti). Every Ratna Gems listing gives the weight in both carats and ratti.
How to compare pearl prices. Quoted prices for pearls of the same description vary widely from shop to shop, so judge the pearl itself on lustre, nacre, surface and size, and compare the per-carat rate, never just the total. At Ratna Gems, freshwater cultured pearls cost ₹150 per carat — for example a 10.18 carat (11.19 ratti) round pearl costs ₹1,527 — and keshi pearls mostly ₹450 per carat, such as a 4.05 carat (4.45 ratti) button keshi for ₹1,823 (October 2026). Fine South Sea and Akoya pearls cost considerably more, and natural Basra pearls are priced as rare antiques.
Step 7: Purchase from a Reputable Seller
Buy from a seller who states plainly whether a pearl is natural or cultured, and which type, and who provides a laboratory report with its weight and measurements and a clear return policy. Every Ratna Gems pearl ships with a report from an independent, ISO-certified laboratory at no extra charge. Our guide to buying gemstones online safely explains how to verify a report.
Why Buy Your Pearl from Ratna Gems?
At Ratna Gems, we describe every pearl plainly and price it openly:
- An Independent Lab Report With Every Pearl: every Moti ships with a report from an independent, ISO-certified laboratory at no extra charge, and you can add a GII, IIGJ or IGI report on the product page, priced by carat weight.
- Named Plainly: cultured pearls are sold as cultured, with the type (freshwater or keshi), the weight in carats and ratti, and the price per carat on every listing.
- Help When You Need It: questions answered before and after you buy, and a 7-day return policy for eligible items.
Frequently Asked Questions
What is the difference between a Basra and a South Sea pearl?
A Basra pearl is a natural pearl from the Persian Gulf, making it extremely rare and valuable. A South Sea pearl is a cultured pearl, grown with human intervention in the Pinctada maxima oyster. While South Sea pearls are the most valuable cultured pearls, natural Basra pearls are in a different league of rarity and price.
Is a Keshi pearl a natural pearl?
A Keshi pearl is a fascinating byproduct of the culturing process. It is not technically a natural pearl because it forms in a cultured mollusk, but it is 100% nacre, similar to a natural pearl, as it does not contain a bead nucleus. They are prized for their unique shapes and high luster.
Which pearl is preferred in Vedic tradition?
A natural pearl such as a Basra is the most prized, but it is very rare and costly. Most people today choose a cultured pearl with good lustre and thick nacre, and many prefer keshi, which is solid nacre with no bead inside. Your own astrologer or Pandit ji is the person to ask.
How should I care for my Pearl jewelry?
Wipe your pearls with a soft, damp cloth after each wear to remove oils and sweat, and put them on after perfume and cosmetics. Never use ultrasonic or steam cleaners or harsh chemicals. Store them separately in a soft pouch so harder jewellery cannot scratch them.
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