Help Replacing crystal!

I’m new to the forum and hoping to get some guidance. I have an Omega from the late 1950s with a cal. 490 movement and case reference 14716/7-3 SC. The crystal is scratched and cracked, so I’m looking to replace it.

I’m pretty new to watch repair and not entirely sure how to go about sourcing the correct crystal for this case. From what I understand, it should be an acrylic (hesalite) crystal, but I’m unsure on sizing or the correct part number.

Any advice on:

• Determining the correct size
• Recommended suppliers
• Whether I should be looking for a tension-fit crystal or something specific to this case

Thanks in advance for the help.

Thank you for the information! Is
Thank you for the information! This is a great help in my restoration.