Blue Sapphire vs Tanzanite: The Difference, Identification and Which One to Buy

Quick Answer

Blue sapphire belongs to the corundum family (hardness 9), and in Vedic astrology it is the established navratna gemstone for Saturn, considered the fastest and most unpredictable in effect among all the navratna — which is why a trial period is considered essential before wearing it permanently. Tanzanite belongs to the zoisite family (hardness only 6–7, considerably softer than blue sapphire), was discovered in 1967 in Tanzania’s Merelani Hills region, and is found nowhere else in the world. Since tanzanite is a twentieth-century discovery, it simply isn’t possible for it to have any ancient Vedic astrological history.

Introduction

Deep blue has always been considered majestic and appealing, and both blue sapphire and tanzanite are extremely popular in this regard. But there’s a clear difference in their hardness, care requirements, origin, and astrological significance. This is important to understand, especially if you’re buying “blue sapphire” on astrological advice, or simply looking for a beautiful blue gemstone.

The Difference in Chemical Composition and Hardness

Blue sapphire belongs to the corundum (aluminium oxide) family, with a hardness of 9 on the Mohs scale — this makes it extremely durable. Tanzanite is a variety of the zoisite mineral family, with a hardness of only 6 to 7 — meaning it’s a notably softer and more brittle gemstone compared to blue sapphire, and needs to be handled with greater care.

Colour Behaviour — Pleochroism vs Deep Velvety Blue

One of tanzanite’s distinctive traits is its pleochroism — meaning the same stone can show different colours depending on the viewing angle, sometimes blue, sometimes violet, and sometimes with a burgundy hue. Blue sapphire is known for its deep, velvety blue colour, which is the distinctive hallmark of corundum. The colour of both gemstones may look somewhat similar at first glance, but tanzanite’s angle-dependent colour shift gives it a distinct identity.

The Difference in Origin

Blue sapphire’s major historical sources include Kashmir, Sri Lanka, and Burma (Myanmar) — meaning it comes from several different geographic regions. Tanzanite’s situation is completely different — it’s found in only one place in the world, the Merelani Hills region of Tanzania (near Mount Kilimanjaro), and it was only discovered in 1967. This “single-source” identity makes tanzanite geologically very special.

The Difference in Astrological Significance

In Vedic astrology, blue sapphire is considered the established navratna gemstone for Saturn, and according to traditional belief its effect among the navratna is considered the fastest and most unpredictable — if it suits you, the effect shows quickly, but even if it doesn’t suit you, the effect can appear just as quickly. This is exactly why a trial period before wearing blue sapphire permanently, along with direct advice from a qualified astrologer, is considered essential. Tanzanite, by contrast, has no ancient Vedic astrological history at all — since it was discovered in the twentieth century, it simply cannot be part of the navratna or any scripturally valid substitute system.

Quick Facts

Feature	Blue Sapphire	Tanzanite
Mineral family	Corundum	Zoisite
Hardness (Mohs)	9	6–7
Distinctive optical property	Deep velvety blue colour	Pleochroism (blue/violet/burgundy)
Origin	Kashmir, Sri Lanka, Burma	Only Merelani Hills, Tanzania
Discovery	Known since ancient times	1967
Astrological status	Established navratna (Saturn), fastest-acting	No classical tradition (modern discovery)
Care	Relatively less caution needed	Avoid ultrasonic/steam cleaning

Expert Tip: Never have blue sapphire set directly into a permanent ring — wear it in a loose ring or tied in a thread for the trial period, so you can remove it immediately if you feel any discomfort. With tanzanite, the biggest caution is different — never clean it with an ultrasonic or steam cleaner, and remove it during heavy work, since its relatively soft structure can be damaged easily.

Buying Advice

If your purpose is astrological and you need “blue sapphire” for Saturn, buy a certified natural blue sapphire — tanzanite is not a scripturally valid substitute, and blue sapphire should always be worn only with a trial period and direct advice from a qualified astrologer. If your purpose is purely jewellery and beauty, tanzanite is a special option because of its unique pleochroism and rarity — just be sure to care for it according to its delicate nature. In either case, always confirm the species on the certificate, and contact us for quotations from the right jeweller.

Key Takeaways

• Blue sapphire is corundum (hardness 9); tanzanite belongs to the zoisite family (hardness 6–7) — tanzanite is considerably softer and more delicate.
• Blue sapphire is the established navratna for Saturn in Vedic astrology, considered the fastest-acting among the navratna, and should never be worn without a trial.
• Tanzanite was discovered in 1967, so it can’t have any ancient Vedic astrological history.
• Tanzanite is found only in Tanzania’s Merelani Hills, while blue sapphire comes from several geographic sources.

Conclusion

Blue sapphire and tanzanite are both exceptional gemstones in their own right — one for its classical astrological depth and intense effect, the other for its rarity and unique colour shift. The right choice depends on whether you’re seeking blue sapphire on astrological advice or simply looking for an exceptional blue gemstone. Contact us for certified quotations on any gemstone.