Yes if it is 12V, and not a 12V battery which could be up to 14V...
12V-2.3V = 9.7V across the resistor worst case.
R = 9.7V/0.7A = 13.85 ohms so chose 15 ohms. Two by 27 ohm in parallel is marginally low, too close for this situation.
Current with Vf = 2.5V = 9.5/15 = 633mA
Current with Vf = 2.3V = 9.7/15 = 646mA
Power in resistor = 9.7 x 9.7/15 = 6.27W
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Therefore you need a 10 or even 20W resistor. A 5W resistor is over-rated. The ten watt one will run quite hot. It is better with a heatsink.
If you work out the power for the LEDs above it is only 1.75W or so. The figures are not the proper ones for 3W. However I looked up the 3W red LED and found the same figures as above. I guess this 700mA is for white ones, with about 4V across them and so around 3W. Red ones are still limited to 700mA so not 3W at all, or so it seems!
Thermal Calculations
The lamp itself may need a heatsink. The thermal resistance applies. This is like 8 degrees C temperature rise per watt from junction to case for one I looked up, and 48C/W for another that has to be mounted on a special metal filled circuit board. That would be 14C rise for 8 x 1.75W. Assume max case rating is 85C maximum, for plastics etc. That leads to a junction of 99C which is fine, within its limits, some are rated 120C, some 150C. I think 50C is a better case temperature to aim for, still very hot to touch, but leaving room for hot days. For an air temperature of 25C, this means we need a heatsink of 14C/W from the case to the ambient. We are ignoring the connection from case to heatsink here, so I would go for a 10C/W heatsink. How you do that depends on the LED itself. Look up heatsinks with this rating, and you will see how big they are, and whether you can adapt them. Power Past Life Regression.::
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Go to www.digikey.com and get your resistors. If that link is not correct look up "Digikey" and go there that is where you get them.
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Looking for resistors for 3w power lamp (red 2.3 -2.5v, 700ma, 625k) need15ohm 5w for 12v supply?