When estimating the fair value of shares or share options at the grant date, several conditions are considered. These include:

1. Market conditions: These refer to the prevailing market circumstances that influence the value of the underlying shares. Factors such as the current stock price, market volatility, risk-free interest rates, and the expected life of the share option are all taken into account. The Black-Scholes model or other option pricing models may be used to incorporate these market conditions.

2. Service conditions: These relate to the employee's continued service with the company as a requirement for vesting the share options. The period of service until the vesting date is an essential factor in determining the fair value, as it affects the probability of the employee fulfilling the service condition.

3. Non-market performance conditions: These are conditions tied to the performance of the employee, the business unit, or the company as a whole, which must be met for the share options to vest. Examples include achieving certain financial targets, sales growth, or other performance metrics. The likelihood of meeting these conditions also impacts the estimated fair value of the share options.

These conditions are typically incorporated into the valuation model to determine the appropriate fair value of the share options at the grant date, in accordance with accounting standards such as International Accounting Standard 2 Share-based Payments (IAS 2) or ASC Topic 718 Compensation - Stock Compensation in the United States.