Australian 1981 2 cent coin 1981 2 cent, No SD Mintmark
The 1981 Australian 2 Cent with NO SD Mintmark seems to be a popular choice along with the most investment potential, considering PCGS graded coins.
This is a rare coin, in my opinion. I have sighted / noted the prices of what the market is currently achieving, as of June 2020 on eBay below:
1981 2c No SD Mintmark PCGS MS64RD $600 AUD
1981 2c No SD Mintmark PCGS MS64RD $580 AUD
1981 2c No SD Mintmark PCGS MS63RD $695 AUD
1981 2c No SD Mintmark PCGS MS63BN $495 AUD
1981 2c No SD Mintmark PCGS MS62BN $395 AUD
1981 2c No SD Mintmark PCGS MS62BN $299 AUD
1981 2c No SD Mintmark PCGS MS62BN $395 AUD
1981 2c No SD Mintmark PCGS MS61BN $295 AUD
Looking at the results from the above mentioned it seems that the Mint State Red coins are on the rise and have the most demand and investment potential. Never the less, the Mint State Brown coins are also desirable and have investment potential.
On the other hand, looking at other dates of the 2 cent coin with the missing SD Mintmark, examples of a 1967 2 cent with No SD Mintmark coin with a PCGS grade of MS63RB is going for $595 AUD.