Jellybean has proven to be a vast improvement over ICS as most Jellybean users have experienced. The performance, the smoothness, the functionality all are a level above ICS. So why wouldn’t everyone want a taste of Jellybean. All Xperia 2011 users are in luck as the Xperia division of CyanogenMod team – FXP(Free Xperia Project) team haven’t yet abandoned you. CM 10 was in the alpha stage for a very long time for the Xperia 2011 series, but it finally has reached a much more usable release. Most of the bugs are fixed except a select few which can be neglected over the overall better performance. Users of Xperia Ray are especially lucky as this excellent piece of hardware works excellent with CM10.

Caution: Flashing a new ROM will delete all your data be sure of making a backup.

Now let’s focus on the requirements to get CM10 on your Xperia Ray(ST18i):

• Unlocked Bootloader.
• Download this CM10-FXP213.zip 
• Flashtools
• Gapps flashable zip

Process:

1. Extract the “boot.img” file from the zip you downloaded.
2. Place both the CM10 and gapps flashable zips in your phones sdcard.
3. Install flashtools.
4. Refer to this guide to flash the “boot.img”(kernel)
5. Once complete with the process, reboot your device and keep pressing the volume up button till your device  enters recovery mode.
6. Now navigate to “factory reset” and select it by pressing the home button. Use volume keys to navigate up and down.
7. Once factory reset is done navigate to “mounts and storage” and “format /system” partition.
8. Now press the back button and navigate to “install zip from sdcard” and select the CM10 zip file you downloaded earlier.
9. This process can take a while.
10. Once finished flash the gapps flashable zip.
11. Now you can reboot into system to enjoy the sweet taste of jellybean on you Sony Ericsson Xperia Ray(ST18i)

Note: It is common for the first boot to take a while!