[Gaming Mechanical Keyboard under Rs.7000]

Hi' I searched for some devices, But not an expert, but I can give a few ideas for you.

Your budget may not be enough to meet all your needs. You have to compromise on some aspects. 

You can go with something like,

Corsair K100 RGB Optical  (The best gaming keyboard)

Switch: Corsair OPX

Size: Full size

Backlights: RGB

Passthroughs: USB

Media Controls: Dedicated

Wristrest: Detachable

Keycaps: PBT double-shot

Mountain Everest Max ( The best modular gaming keyboard)

Switch: Cherry MX Red, Blue, Brown, Silver

Size: Full size or TKL

Backlight: Per-key RGB

Passthrough: USB 3.2 Gen1

Media controls: Dedicated unit

Wristrest: Magnetic, plush

Keycaps: ABS

Razer Cynosa Chroma(The best membrane gaming keyboard)

Interface: Wired USB

Keyboard backlighting: Per-key RGB

Programmable keys: All

Features: Per key RGB lighting, supports Windows 7+ and OSX 10.8+