Perfectly Straight Hair Without Compromise
Struggling with hair that frizzes after styling, stubborn curls that won’t straighten, or concerns about heat damage? The KINUJO Pro Sapphire Straightening Iron, co-developed with professional hairstylists, offers a solution.
Equipped with a unique ‘Sapphire Plate’ designed specifically for hair straightening, it reduces stress on hair cuticles.
With professional-grade dehydration performance, it delivers powerful straightening power, achieving smooth, even results from roots to tips—even on stubborn curly hair.
This is a professional-grade straightening iron that elevates your styling satisfaction.
▪ Unique ‘Sapphire Plate’ Designed for Hair Straightening
By reducing friction, it minimizes stress on the hair cuticle, reducing mechanical strain (tensile stress) by approximately 50%* while still delivering strong straightening power. It preserves hair softness and shine.
※ Manufacturer test. Testing institution: New Ishikawa Industrial Technology Comprehensive Research Center, Material Response Support Center.
Measured tensile stress on hair samples using Sapphire Plate vs. non-processed plate.
▪ Professional-Grade High Dehydration Effect for Powerful Straightening
Designed to enhance moisture activity and dehydration efficiency, it balances internal moisture in hair while delivering even heat distribution.
Effectively controls excess moisture, allowing consistent heat penetration from root to tip, resulting in stable, straight hair even on thick, curly hair.
▪ Plate Design Reaching to Roots and Approximately 24mm Width
Features a plate design that easily reaches the roots, scalp, and hairline areas. This ensures thorough straightening at the base of the hair.
| Feature | Detail |
|---|---|
| Plate Type | Sapphire Plate |
| Heating Technology | Professional dehydration system |
| Plate Width | Approx. 24mm |
| Heat Range | Root to tip |
| Target Hair Type | Curly, thick, or resistant hair |
FAQ
How does the Sapphire Plate reduce damage to hair?
The Sapphire Plate reduces friction and stress on the hair cuticle, lowering mechanical strain by about 50% according to manufacturer testing. This helps preserve hair softness and shine while delivering strong straightening power.
Can this iron effectively straighten thick or curly hair?
Yes. With its professional dehydration technology and even heat distribution, it provides consistent straightening from root to tip, even on stubborn curly or thick hair.
Is the plate design suitable for use on the roots and hairline?
Yes. The plate design allows for easy access to the roots, scalp, and hairline, ensuring thorough straightening at the base of the hair.

Hannah Alsop –
I’ve tried several straighteners before, but this one actually straightens my thick curly hair without making it dry or brittle. The Sapphire Plate feels smooth and the heat is even. I can now style my hair in the morning without worrying about it frizzing back.
Amelia Coleman –
After using it for a week, my hair feels softer and shinier. The roots are straight now, and there’s no more unevenness at the ends. I appreciate the design that reaches the roots easily.
Victoria Stewart –
It works well on my medium curly hair. The straightening is even, and I don’t feel the heat damage like with other irons. A bit heavy, but worth it for the results.
Jack Coleman –
I used it on my thick, wavy hair and was surprised by how well it straightened without drying out the ends. The plate design helps reach the roots, and the hair stays smooth throughout the day.
Chloe Parr –
Good performance for curly hair. The heat distribution is even, and I notice less frizz. It takes a bit of practice to get the temperature right, but once I do, it’s very effective.