Revelation 3:18 I counsel thee to buy of me gold tried in the fire, that thou mayest be rich;
As I mentioned in the answer to your previous question Gold represents faith. Gold is the most precious commodity in the service of man. Faith is the most precious attribute in the service of God.
Hebrews 11:6 But without faith it is impossible to please him: for he that cometh to God must believe that he is, and that he is a rewarder of them that diligently seek him.
Peter connects faith with gold. As gold is refined by the heat of a furnace and the dross is melted out so faith is tried in affliction and our character is refined.
1 Peter 1:7 That the trial of your faith, being much more precious than of gold that perisheth, though it be tried with fire, might be found unto praise and honour and glory at the appearing of Jesus Christ:
To ‘buy’ is a figure used by God through Isaiah:
Isaiah 55:1 Ho, every one that thirsteth, come ye to the waters, and he that hath no money; come ye, buy, and eat; yea, come, buy wine and milk without money and without price. 2 Wherefore do ye spend money for that which is not bread? and your labour for that which satisfieth not? hearken diligently unto me, and eat ye that which is good, and let your soul delight itself in fatness. 3 Incline your ear, and come unto me: hear, and your soul shall live; and I will make an everlasting covenant with you, even the sure mercies of David.
The exhortation is to make an equal effort to understand the word of God as is made to obtain the necessities of this life.
Genuine faith comes only from hearing and understanding the word of God.
Romans 10:17 So then faith cometh by hearing, and hearing by the word of God.
To buy gold is a figure for strengthening our faith by diligent application to the word of God accompanied by prayer.
2 Timothy 3:15 And that from a child thou hast known the holy scriptures, which are able to make thee wise unto salvation through faith which is in Christ Jesus.
Scripture is the source of the ‘Gold’ of faith that God requires in us. We must make every effort to understand what God has caused to be written for our learning.
2 Timothy 3:16 All scripture is given by inspiration of God, and is profitable for doctrine, for reproof, for correction, for instruction in righteousness: 17 That the man of God may be perfect, throughly furnished unto all good works.
Revelation 3:18... anoint thine eyes with eyesalve, that thou mayest see.
Eyesalve - Greek ‘kollourion’ A preparation composed of various materials and used as a remedy for tender eyelids. A Phrygian powder mentioned by Galen, for which the medical school of Laodicea seems to have been famous (see Ramsay, The Letters to the Seven Churches of Asia)
The figure of anointing the eyes with an apothecary’s preparation for improving vision denotes an application to restore their spiritual vision. This can only refer to applying themselves to the will of God as revealed in scripture. They had become lukewarm – lacking zeal for the service of God.
A reappraisal of their lives was required in the light of the commandments of Christ. They were no longer doing the will of God wholeheartedly.
I hope you have found this helpful.