~Four days to fully immerse yourself in gemstones, including the pre-sale of the new "Gemstone Encyclopedia 3D Stickers," special offers for posting on social media, and photo spots~
KARATZ Co., Ltd., which operates " KARATZ Gem Magazine ," Japan's largest specialized gem information media, and " KARATZ STORE ," a specialized online store for gemstones, will be holding a limited-time summer pop-up store at " 2k540 AKI-OKA ARTISAN ," a creative space under the elevated railway tracks between Akihabara and Okachimachi stations on the Yamanote Line, for four days from Thursday, July 30th to Sunday, August 2nd, 2026.
At the venue, in addition to displaying and selling a wide variety of loose gemstones and jewelry, we will be offering a "custom-made consultation" where you can create a one-of-a-kind original piece of jewelry, as well as many "experiential contents" and limited-time events that will be making their debut this time, to welcome you.
What is a KARATZ pop-up store?
Gemstones aren't just for admiring in museums or for wearing as expensive jewelry.
At KARATZ, we want you to experience the joy of actually holding, comparing, learning about, and finding that one special stone that's just for you.
The KARATZ Pop Store is a limited-time shop operated by KARATZ, the company that runs "KARATZ STORE," one of Japan's largest online gemstone retailers, handling over 10,000 natural gemstones and jewelry items, from famous gemstones to rare stones. Over 1,500 items carefully selected by gemologists from the extensive lineup of "KARATZ STORE" will be gathered in Akihabara. This is a rare opportunity to see the gemstones from "KARATZ STORE," which are usually only sold online, up close.
We offer a wide range of products that can be enjoyed not only by gem enthusiasts but also by those who have not had much opportunity to interact with gemstones before. These include beautifully cut gemstones crafted by skilled polishers both in Japan and abroad, meticulously made ready-made jewelry, rough stone polishing kits, and jeweler's tools.
We have knowledgeable staff on hand to help you choose the perfect piece of jewelry, so even if you're not familiar with jewelry and don't know how to select it, please feel free to visit us.
In addition to selling gemstones, we also offer a variety of experiences related to gemstones, such as custom order consultations, gem gacha (capsule toy vending machine), and photo spots.
Event Overview
■Location: 2k540 AKI-OKA ARTISAN Private Event Space (C-1)
(5-9 Ueno, Taito-ku, Tokyo) *Under the elevated tracks between Akihabara Station and Okachimachi Station on the Yamanote Line
■Period: July 30th (Thu) – August 2nd (Sun), 2026
■Business hours: 11:00 – 19:00
*Opening time on the first day (July 30th) is 13:30, closing time on the last day (August 2nd) is 18:00.
*Entry may be restricted depending on the crowd situation.
[Experience Program 1] Turn your favorite gemstone into a one-of-a-kind piece of jewelry. 'Custom Jewelry Consultation'
You can have a one-of-a-kind original piece of jewelry made using gemstones you find at the venue on the day, or loose gemstones you have previously purchased or acquired from Carats.
There are approximately 40 different design frames to choose from.
We offer a wide variety of frames, from simple designs that just hold the gemstone to glamorous designs adorned with diamonds as accent stones.
You can choose from items such as rings, pendant tops, necklaces (with chains), earrings, and charms, and we can also create half-eternity rings.
At a pop-up store, you can see how the gemstones look in actual settings and compare them to the finished product, allowing you to find your ideal design.
Customization to fulfill your specific desires
It is also possible to change the side stones to something other than colorless diamonds as an option.
Choose from our extensive lineup of colored diamonds, rubies, sapphires, emeralds, and more.
In addition, you can customize the details to your liking, such as applying a matte finish or engraving to the surface.
If you're unsure about the design or arrangement, please feel free to consult our staff. We'll listen to your wishes and help you create your ideal piece of jewelry.
*Some slots may have limited size or cut options.
*We do not accept jewelry purchased from other companies.
Past Project Examples
[Experience Event 2] What you get is a surprise! "Gem Gacha" makes its first appearance at the event!
The popular "Gem Gacha" from "KARATZ STORE" is making its first appearance at this event!
Choose one from our pastel-colored capsules and try your luck! It's a great way to commemorate your visit.
A luxurious lineup with no duds.
The grand prizes include a rare "Paraiba Tourmaline from Mozambique" with a dazzling neon blue color, and an "Afghan Hauyne" with a certificate of authenticity.
In addition, the set includes high-quality gemstones that you'll be delighted to receive, such as cat-cut pink tourmaline, mahenge spinel, color-change garnet, and a set of two sphalerite stones.
Product overview
Gem Gacha
Price: 3,500 yen (tax included)
*Limited to one entry per person per day.
This offer will end once supplies run out.
[Pre-sale] An evolved version of the highly popular series! "Authentic Gemstone Encyclopedia 3D Stickers" Vol.2 & Vol.3
We are pleased to announce a limited-time pre-sale of the latest installment of our popular "Authentic Gemstone Encyclopedia 3D Stickers," ahead of its general release scheduled for mid-August!
Vol.2 Birthstones: A collection of gemstones for each month from January to December. Enjoy the fun of finding the birthstone of your family or loved ones.
Vol.3 Inclusions: An ambitious work that delves into the mysterious microcosm unfolding within gemstones, a must-see for enthusiasts.
Evolved shine and texture
Compared to the previous model, the number of facets in the cut has increased, enhancing the three-dimensional effect. Furthermore, the use of rainbow glitter that shines in seven colors has increased the sparkle. Enjoy a more realistic gemstone feel.
Product overview
Authentic Gemstone Encyclopedia 3D Stickers
Volume 2 Birthstone
Volume 3 Inclusions
Price: 660 yen each (tax included)
▶ Special website for "Authentic Gemstone Encyclopedia 3D Stickers"
*Purchase is limited to 5 tickets per person.
[Special Offer 1] Post on social media to receive a "Custom-Made Jewelry Coupon"!
Customers who post on social media while at the venue and show the screen to a staff member will receive a special coupon that can be used for custom-made jewelry.
You can use this coupon not only when ordering on the day, but also when ordering through the " KARATZ STORE " (online store). Take this opportunity to try your dream custom-made experience.
*This offer is limited to one use per person.
[Special Feature 2] A special photo spot where you can beautifully capture your favorite "moment"
A special "photo spot corner" will be set up inside the venue where you can take pictures of the loose gemstones and jewelry you purchased, as well as the results of your gacha (capsule toy) experience.
Capture the best expressions of your new treasure in photos and share them on social media!
Event Details
[KARATZ Pop-up Store]
■Location: 2k540 AKI-OKA ARTISAN Private Event Space (C-1)
(5-9 Ueno, Taito-ku, Tokyo) *Under the elevated tracks between Akihabara Station and Okachimachi Station on the Yamanote Line
*4-minute walk from JR Okachimachi Station South Exit / 6-minute walk from JR Akihabara Station Electric Town Exit
■Period: July 30th (Thu) – August 2nd (Sun), 2026
■Business Hours:
Thursday, July 30th, 1:30 PM – 7:00 PM
July 31st (Friday) 11:00 AM – 7:00 PM
August 1st (Sat) 11:00-19:00
August 2nd (Sunday), 11:00 AM – 6:00 PM
*Entry may be restricted depending on the crowd situation.
*The contents of the sale are subject to change without notice.
What is KARATZ?
KARATZ Co., Ltd.
"We want more people to enjoy gemstones." "We want to bring smiles to everyone's faces with the brilliance of gemstones."
With that wish in mind, we are a company that disseminates a wealth of information related to gemstones.
In addition to disseminating information through web media and social media, we also give lectures at the Gemological Institute of America (GIA) and the International Jewellery Tokyo (IJT), and hold workshops for elementary school students and events for gem enthusiasts in Tokyo, engaging in activities to convey accurate knowledge to many people through various means.
In recent years, she has also focused on book production, and her published works include " A Gemstone Encyclopedia with Beautiful Photographs: From Famous Stones to Extremely Rare Stones " (Nihon Bungeisha) and " The Little Book of Gemstones " (Liberal Publishing).
KARATZ's initiatives
KARATZ Co., Ltd. was founded with the desire to provide a place where gemologists can share accurate knowledge about gemstones and where anyone can easily seek advice. Since its establishment, the company has continued to disseminate a wealth of information related to gemstones, primarily through its specialized gemstone information media " KARATZ Gem Magazine" (https://karatz.jp/), as well as utilizing social media such as X (formerly Twitter), Instagram, and Facebook.
KARATZ Gem Magazine continues to provide information on a wide range of topics, including not only basic knowledge about gemstones, but also the differences between genuine and fake gemstones, how to distinguish them, and interviews with prominent figures in the gemstone industry.
It is characterized by having a large readership not only among the general public but also within the industry, and with over 200,000 monthly visitors, it is one of the largest jewelry-specialized media outlets in Japan.
In addition to operating " KARATZ STORE " (https://store.karatz.jp/), a specialized online jewelry store boasting one of the largest selections in Japan, we have also been active in spreading accurate knowledge about gemstones while allowing people to experience and enjoy them firsthand. This includes hosting gemstone workshops for elementary school students in Tokyo in 2018 and 2019, a parent-child gemstone workshop at the Benesse Corporation-sponsored event "Tamahiyo Family Park" in the fall of 2019, and experiential events for gemstone enthusiasts in July and September of 2020.
Scenes from past events
We will continue similar initiatives, primarily through the internet and events, and aim to conduct business activities that create an environment where all people who love gemstones can enjoy a rich life with them.
Carats Co., Ltd. Company Profile
Company name: KARATZ Co., Ltd.
Representative: Keiichiro Koyama, Representative Director
Head office location: Office R4F, 5-26-4 Ueno, Taito-ku, Tokyo
Establishment date: November 29, 2017
Business activities: Operation of a specialized gem information media, a gem e-commerce site, and a gem appraisal app.
Company website: https://karatz.co.jp/
<Operating Services>
・KARATZ Gem Magazine: https://karatz.jp/
・KARATZ STORE: https://store.karatz.jp/
・KARATZ AUCTION (Karaoku): https://karatz.jp/karaoku/
・KARATZ Official X (old Twitter): https://x.com/karatz_official
・KARATZ official Instagram: https://www.instagram.com/karatz_official
・KARATZ official Facebook: https://www.facebook.com/karatz.jp
・Representative Koyama X (old Twitter): https://x.com/keiichiro_oyama
・Representative Koyama note: https://note.com/keiichiro_oyama
・KARATZ Official Youtube: https://www.youtube.com/channel/UCePLrhj37krb5gaoSJvOcVg
[From KARATZ Co., Ltd. press release ]
