Users with select Nokia Lumia handsets now have access to a new firmware update called "Black" that updates your device with new capabilities. But what is this mysterious "Black" update, and which phones can already access it?

Nokia "Black" is a firmware update that accompanies Windows Phone 8 Update 3. If you recall Windows Phone 8 Update 2 (then called GDR2), you may recall that it was accompanied by another Nokia firmware update called "Amber." I wrote about those releases in Lumia 1020: A Peek at GDR2 and Amber, and of course provided a broader overview of GDR2 in my Complete Guide to Windows Phone 8 GDR2.

So what's happening with "Black"?

First arrived with the Lumia 1520. Nokia "Black" first shipped with the Lumia 1520 in November, though if you check for updates on that device now you'll see that it's being updated. So get the update.

Lumia 1020 on AT&T. If you're using a Lumia 1020 on AT&T Wireless now, as I am, you can check for updates: The "Black" firmware update is available on that device now as well.

Other phones? This update will start rolling out to other Nokia Lumia owners around the world in early 2014 as planned, Nokia tells me.

It ships alongside Update 3. If you're getting "Black," that means you're getting Windows Phone 8 Update 3 (from Microsoft) as well. If you installed Update 3 previously using my tip Windows Phone 8 Update 3: Update Your Handset Today!, you'll just get "Black."

Glance screen improvements. The cool Glance screen—which shows a clock when the device isn't being used—is updated with new Night Mode colors (green and blue, in addition to red) and notification support. I don't see a way to control notifications, however, so it must just use whatever is configured to work with the normal lock screen. (Nokia says it's new emails, missed calls, text messages and more.")

RAW support. "Black" lets you save your photos in RAW format, which may be desirable for professional photographers. To use this, go to Settings in Nokia Camera and choose "JPEG (5 MP) + DNG (34 MP)" under Capture Mode. DNG stands for "Digital NeGative."

Camera improvements. Perhaps answering why I find Lumia 1520 pictures to be slightly better than those taken with the superior Lumia 1020 camera, "Black" also adds new camera algorithms for JPEG processing, white balance and noise reduction. You can now launch Nokia Camera from a PIN-locked lock screen, which was possible previously with the built-in Camera app only.

Bluetooth update. With "Black," the Bluetooth technology on your device is upgraded to Bluetooth 4.0 LE (on supported phones, like the Lumia 1020). For now, this doesn't change any built-in Bluetooth functionality, but that could change in the future. (Update: Nokia says that this support allows consumers to easily sync accessories such as heart rate monitors with their Nokia Lumia to create differentiated experiences with apps like Adidas miCoach.)

Lock Screen Options. Now, you users can opt for either portrait or landscape mode to accommodate even greater customization and personalization.

Let me know if you find out anything else about "Black."