GIA Certified

We exclusively propose diamonds certified by the GIA, the one and only grading authority for the diamond trade worldwide. Other laboratories over-grade stones, giving you a false sense of quality and value.

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100% Custom

The perfect engagement ring does not already exist in a display. It should be custom made with you, for you. Our onsite expert craftsmen will make that dream a reality.

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Friendly Support

At our studio, you will be treated in a private setting with all the focus on the making of your diamond purchase experience the most personal, relaxing, and educational diamond buying experience.

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Personalized Service

Our best engagement rings are created with a personalized service. The service begins with a consultation with Sevan, who will learn more about you and your inspiration, helping you to develop your ideas and final vision.

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A Brief History…

Design by Sevan - Custom Diamond JewellerySevan Tosun was born in 1977 in Istanbul, Turkey, the former capitol of the Byzantine and Ottoman Empires and home to a tradition of fine jewelry spanning over two millennia. At the age of 10, Sevan carried on his father’s legacy and began a full-time apprenticeship with one of the finest jewelry houses in Istanbul. By age 16, he had learned every facet of the trade, cultivating the highest level of skills a jeweler could achieve in metal, diamond setting and design, imagining intricate designs and creating pieces from start to finish.

With an amazing array of skills and dreams of a better life, Sevan left his roots in Istanbul as a teenager and headed for Canada with just $250 in his pocket. Connecting with a relative who had already emigrated to the Canada Sevan arrived in Toronto industry. Within a few years, Sevan developed a reputation as the finest jeweler in the area, and in 2000, he founded A.S.T.Jewelry ,Today, Design by Sevan A.S.T Jewellery stands as one of the premier Engagement Ring boutiques in Fashion district Toronto.


  • Sevan was absolutely amazing to deal with. He found the perfect diamond and complemented it with an incredible design. I live in Ottawa and his store is in Toronto, and I never even needed to make the trip. We exchanged emails, designs, and phone calls in order to complete my request and my ring is even more beautiful than I could have imagined. I would absolutely recommend him to anybody and everybody I know. Thank you Sevan for my perfect dream ring..

    Vanessa Sanschagrin
  • We had an amazing experience with Sevan! We had to have our wedding rings designed on short notice and Sevan delivered on time and the rings turned out absolutely beautiful. The experience at his studio is pleasant and he is very patient. He provides a lot of valuable information with regards to style, and type of metals that would be optimal for certain designs. Sevan’s experience shows. He is a true professional and knows his art form in out. We would recommend Design by Sevan to anyone looking to get a truly personalized engagement ring. Thank you Sevan.

    Anna Gondzik
  • Buying a ring from AST was a fantastic experience!! Can’t say enough nice things about Sevan. He runs an honest, pressure free business and has become my go to guy for all my jewelry needs.

    If you’re looking for a diamond ring for that special someone Sevan will make you the ring of your dreams for a fraction of the cost of the big guys… and treat you with respect along the way.

    Could not be happier!! Highly recommended!!

    Dan Pifs
  • My girlfriend and I (now fiancée) were referred to Sevan at AST Jewellery by a friend of ours.

    Taking a look at his site we found something we wanted (she wanted a coloured stone and we landed on sapphire) to which we promptly set up a time to go meet him and try it on!

    Not only was he quick to respond but he made us feel very comfortable with our flurry of questions and took the time to explain various cuts, clarity, etc. This man knows his craft very well and we could tell how passionate he is about it.

    We figured out what we wanted and moved forward. Sevan takes you along every step of the way, is honest, assuring, kind and simply a genuinely nice person. When making a big purchase and a big decision like getting engaged it just amplifies the excitement when the person you’re buying the ring from is so fantastic.

    A brilliant experience. Highly recommended and we’ll be back for the wedding bands and be referring any of our friends to him.

    Thanks Sevan!

    Justin Cumby
  • I was referred to Sevan and AST Jewellery by a friend. Prior to meeting Sevan, I met many jewellers and saw many diamonds and rings. Sevan was very passionate, straight forward, and honest about everything. More importantly he was more than willing to work with me and my vision. He was not only able to teach me more about diamonds but he was able to help me find one that was perfect. I have since proposed and my fiancé is in love with the ring. I will be going back to Sevan for the wedding bands and recommending him and AST Jewellery to all my friends and family.

    Kadir Debello
  • Sevan is the man! I had a very stressful experience looking for a diamond engagement ring before finding Sevan at AST Jewellery. He is a very likable and easy to speak to and gave me great advice through the whole process of designing a custom ring. He seemed more interested in creating a tasteful ring rather then selling me the largest diamond I could afford which was really appreciated. Also the rings he has on display are very well designed and crafted which left me confident I was in good hands. I had some ideas about creating a custom ring and he was able to take them and create a ring that went above and beyond my expectations. I am very pleased with the service and the ring I got at AST Jewellery and will definitely be returning to get wedding bands done or any other custom jewellery in the future.

    Nate Fisher

For many jewellers, making jewellery is a profession – for Sevan, it is an identity.

If an engagement ring design has caught your attention, make an enquiry with us today.

Specializing in Custom Diamond Engagement Rings

NO SALES PRESSURE SHOWROOM – No unwanted sales pressure. We promise!

  • Our trained consultants are NOT on commission. That’s what separates us from other jewellers. Feel free to come in and browse our store at your own pace. When you’re ready, we will be happy to answer any question you have.
  • Our personalized service focuses specifically on the customer. Visit our store and you’ll see we are truly on your side.
  • There’s no jewellery store better equipped to meet all of your engagement ring shopping needs.
engagement ring marriage proposal

We specialize in designing custom jewellery. If you’ve got an idea for a ring or another piece of jewellery, we can help bring your idea to life and offer advice on the design and details to meet your individual needs.

We design all our jewellery in-house and all commissioned rings are individually made for each client, this making us uniquely suited to offer customers great custom jewellery at affordable prices.

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